John Burns

I got side tracked but I hope to finish this modification today or tomorrow! I got the blower working using the AC wiring harness and AC resistor. My wiring diagram show 2 types of AC systems called "Comfortron" and "Four-Season". I searched and only found 1 reference to "Four-Season" and none for "Comfortron". Did these Montes ever come with the "Comfortron"? I'll post pix of what I'm doing if anyone is interested.

You are correct- the A/C version does NOT have fresh outside air for the 2 L&R vents in the dash, but behind the passenger side kick plate, there is a vacuum actuated fresh air duct. And I agree- trying to put factory air in a non-air car would be way too much work! The firewall rework alone would be brutal. And your second photo is the hen's tooth picture I have been looking for! Now I see that round duct isn't in the firewall- it is off to the side and it goes to the cowl (one one the driver side too). I'm on the fence about trying to add these- it would be a ton of work, but also nice to have a fresh air option other than the kickplate vents. Not sure if the climb is worth the view! Thanks!!

Very cool- that heater box is what I was after. Do you have any photos of the fresh air vents - or the holes for those vents? From what I understand, they are supposed to be under the dash, at the top of the fire wall. One hole on each side that goes into the cowl. At this point, I don't think I'm going to get that ambitious to add them, but I would love to actually see them- I can't find any photos online. Thanks!

I would love to see a whole factory "heater only" set up. I couldn't find any photos online. I can only find the assembly manual photos, but they are missing tons of detail.

Hi Dennis B, I thought you said your car was born with "heater only"! It appears it was an AC car, but maybe someone had removed the evaporator (the big box in the engine compartment) before you got it? I want to do this conversion because the vacuum hose mess under the dash is leaky, and I don't want the factory AC control panel if I don't have AC! I already have the AC delete plate on the firewall inside the engine compartment. Now I am removing all of the vacuum operated stuff under the dash. I have the heater only control panel already and I'm pretty sure I can adapt the cables to operate the doors in the AC box (like I said: stay tuned!). As for the Astro Ventilation, repop kick plates with the knobs / cables are available. I have removed my AC kick plates (passenger side was a vacuum operated vent and drive side has a bolt-on block off plate). I'll post pictures of this whole craziness when I am done! John

Hi Dennis! I was replying to MCfan- he is Dennis too!

Hi Dennis, Thank you very much for the offer! I am going to attempt to adapt the AC heater box to the non-heater controls. That might sound nuts, but I think it might actually be easier than swapping in a factory heater box. I pulled the ac heater box already, removed the diaphragms, and have figured out how I want the various doors to operate mechanically (stay tuned). BUT, for documentation's sake, it would be really cool to see all of the non-AC parts. AC cars are well documented, but I haven't found any good info on a non-ac car. And I have searched many A-body forums! Some things I'd love to know about your car: Where is (was) the "heater resistor" mounted? Where do (did) all three of the control cables go? (Especially the one controlled by the OFF - AIR lever.) What do the factory fresh-air ducts that come from the cowl look like? Did you keep them? There are "fresh air doors" on either side that operate from pulls on the kick plate. I'd love to see a photo of this. One interesting thing I have learned: the non-ac blower wiring and connectors are in every car. If ac was installed at the factory, they installed an ac harness and simply tucked the non-ac wiring and connectors out of the way. Again- I very much appreciate the offer. And if I crash and burn on my current plan, I might hit you up for those parts! Thanks John

Nice! If they are impossible to pull off, then they won't fall off!

Thanks for the thought! (And nice looking small block!) Yes aftermarket starter and I just had to look to see if the stud was removable- it isn't. It is a big block with headers and it is tight, so I'm stuck with the starter. As one of my taglines says: "Did you ever notice that when you buy aftermarket stuff, you have to buy more aftermarket stuff to make it all work?"

My car had factory AC and a long time ago I removed the evaporator box and installed an AC delete plate in the engine compartment. This kept the heat, but I still have all the controls under the dash that are operated by a spaghetti of vacuum tubes. I picked up a non-AC control panel, but there is no way to attach this to the old AC stuff under the dash. And yes, I still want heat! Has anyone ever removed this vacuum spaghetti and the AC box under the dash? It still kinda works, but it is worn out and I just realized it is creating a vacuum leak. Does anyone have a non-AC box that goes under the dash? It appears it is operated with 3 cables. Thanks!

My starter has a male spade connector for the starter wire. I have tried various push on female connectors for many years. They become loose and I've found them barely attached more than a few times. It just happened again... I knew there had to be a better way. I dug around and found these connectors at DigiKey: https://www.digikey.com/en/products/detail/te-connectivity-amp-connectors/63239-1/294488?s=N4IgTCBcDaIIJgCwHYCsqDCAVAtAOQBEQBdAXyA The trick thing about these is that they clip into the little hole in the male spade connector. There is a little lever on them to pop them off. I installed one and pulled pretty hard on the connector and it stayed! Fingers crossed this is the cure.

My simple conclusion & fix: I replaced the factory 90Ω resistor on the back of the gauge with a 100Ω. I simulated the sending unit with resistors from 220Ω to 47Ω and it behaved properly. (Temperature increases as resistance decreases.) Here is what I learned from this adventure: (And please feel free to rebut, correct or clarify my ramblings- I want to document this before I forget it in a few days... I have a couple of other projects coming up. I'll refer back to this to refresh my memory.) The initial problem with my gauge is that it would go to 210° and sit there- even though the engine was running at 165°. I'm pretty sure this is how an idiot light sending unit behaves with a gauge. I installed a Lectric Limited sending unit and the gauge wouldn't come off of 100°. The resistance wasn't dropping enough in the sending unit to move the gauge needle. I tried a sending unit out of my 68 Camaro and at best it would just come off of 100°. I tested 3 different sensors using hot water and watched the resistance behave properly, but none of them would drop low enough to operate the gauge. My gauge needs a 100Ω resistor vs. the factory 90Ω- but why? I'd guess the age of the mechanism in the gauge is the culprit, but I have no idea why changing the resistor corrected this. These gauges are hardly an exact measurement! There are variations in the gauges and sending units. BUT, once they are correct, they are very reliable as a reference- you get to know where the needle is when the engine is running normally. If it starts to creep up (or peg hot), you have issues! No wonder they didn't have actual numbers on temp gauges in the 60's. I'd bet the temp gauges with numbers gave mechanics fits. I don't buy "don't use teflon tape" on the sending unit. Unless you don't know how to apply teflon tape, use it. I bought 2 new sensors and they came with tape already on the threads. Take a resistance reading after you install the sensor if you aren't sure. If you aren't used to measuring resistance with a multimeter, take your time! You have to dig into the contact points with the leads and make sure the number you come up with is repeatable. Measuring voltage is quick- take your time with resistance. Taking the temp gauge out of these cars is a painful experience. Do as much troubleshooting with the sending unit first. If you determine you need to remove the gauge, take your time. Tiny screws and nuts that are hard to access, delicate parts... walk away for a while if you get frustrated. If your gauge doesn't work- what are the symptoms? It sits at 100° and won't go up as engine temp increases: 1) Make sure the wire is on the sensor 2) Test the gauge at the sending unit. With the key on (engine doesn't have to be running), ground the sending unit wire and see if the gauge goes to full hot. If it does, then the gauge is most likely wired correctly. 3) Test the sending unit. Measure resistance ohms (Ω) using a multimeter between the post of the sending unit to ground. Measure this with the engine cold (you will get a high Ω reading). Get the engine hot and measure it again- the resistance will drop to somewhere in the range of 120Ω to 150Ω at an operating temp of 180°. 4) Test the gauge using resistors in place of the sending unit. (You can get a pack of a 1000 resistors with a wide range of resistance for $10 from Amazon. Also make sure you have a bunch of alligator clip test leads ($6 for 20 on Amazon). My gauge needed very low resistance to operate. Lower than the sending unit was able to reach. As I mentioned above, I replaced the 90Ω resistor on the back of the gauge with a 100Ω resistor. The gauge reads too high. (This seems to be the most common problem I read about.) 1) Make sure you don't have an idiot light sending unit. My first sending unit had very high resistance (1700Ω) at room temp. I haven't verified if this is correct for an idiot light sending unit or if it was broken. It would respond eventually as the engine warmed up moving the gauge to 210°, but this was incorrect. 2) The resistance from the sending unit is too low in the operating range. This seems to be a common issue with replacement sending units. Someone makes a variable resistor that can be installed in-line with the sending unit wire to increase the resistance up to 50Ω. OR decrease the resistor on the back of the gauge (opposite of my cure for a low reading). I'm assuming this will work, but I didn't try it. The needle flops around. The gauge either doesn't have proper voltage or ground.

Interesting about the 69 Z/28- I have a 68 Camaro and I swapped the gauge sensor into the Monte to see what it would do. It did read but it was very low. I have an AC Delco sensor G1852 on order from Amazon. One review says "This sensor measures about 550 ohms cold and about 30 ohms hot which is what GM gauges of that vintage require." It is supposed to be delivered late today- and it is supposed to snow tonight (grrrrrrr). I did the hot water test on the NAPA unit and the resistance was similar to the Lectric Limited, so I didn't even try it. I'm going to write a "final conclusion" post when I figure this out (I'm going to get this right or die trying! ). Maybe because my car is so early, it needs a different sensor than later FGMCs?

I will put this on my "I want to do this" list and see if I can make it happen. My "I want to do this" list keeps expanding and available time keeps shrinking!!

I won't I promise! Bad karma for sure!

Hey hey- thanks for the reply! The resistance at 70° is 1200 ohms, but speaking to Mike at Lectric Limited, he told me that room temp isn't a really good indicator of how the sender is going to operate in the operating range. He was a very helpful too and expanded on the "won't work under 180°"... it is more like: you can't really trust the reading below 180°. So I broke out the wife's pots and boiled some water to test the resistance. At 160° I got 165 ohms. This resistance isn't low enough to move the gauge. (At 200° I got 105 ohms.) So I called Redline and I'm not sure if I spoke to Shannon, but whoever it was was very very helpful! He said they recommend NAPA's sending unit. I'm not saying the Lectric Limited unit is wrong or bad- I think there is a lot of variation in the sending units and 50+ year old gauges. I prefer factory gauges and I know they are rarely dead nuts accurate, but they are consistent. Redline also gave me this chart: 100° (bottom scale) - 355 ohms 160° (1/4 scale) - 122 ohms 210° (1/2 scale) - 83 ohms 3/4 scale - 65 ohms 250° (full scale) - 55 ohms Anyway, I'm off to NAPA to pick up the sending unit. I'll let you know if it works!

Hi all! It has been wayyy too long since I've been on these boards. I am trying to get my factory temp gauge to work properly. I searched the site and there is almost an overwhelming amount of information about these gauges. I didn't see anyone with my specific issue. Here goes: I have a the factory temperature gauge inside an otherwise highly-modified gauge cluster! The temp gauge goes to 210 and sits there- the motor runs at 165. I think I might have had an idiot light sending unit. I got a "correct" Lectric Limited sending unit and now the gauge never comes off of 100 (I'm not using teflon tape!) I pulled the gauge and made sure everything is properly connected. I bench tested (and tested in the car) using various resistors and it behaves properly. (100 ohms reads about 160°, and 47 ohms reads something like 250°.) I called Lectric Limited and the guy told me my gauge won't read unless the temp is over 180°. Is that true? He said the factory gauge is only there to tell if the car is running hot. My 68 Camaro factory gauge certainly doesn't operate this way. Is there a sending unit that will enable the gauge to work below 180°? Am I missing something obvious? I'm not an electrical expert, but I've done this long enough to be dangerous. This one is hurting my head! (One other thing I'll mention: the resistor on the back of the gauge is a wire type that is 90 ohms. Most posts discuss a ceramic resistor that reads 80-83 ohms. I can't image a 7 ohm difference being the issue. My guess is this wire resistor is a leftover from 1969 that they used up on early 70s Montes. This car was built September 69.) Help - Thanks! John

Twisting the bulb fixed it somehow, but radio worked with either the button pushed in (bulb off) and the door open, or the button not pushed (bulb on) and door open. It just wouldn't work with the door closed (bulb off). Some strange connection between the door, chassis and bulb? I guess I'll take a closer look at the dome light connections- maybe something is grounding out there. I'll replace the door switch as a matter of course too. And check the radio ground!

I'm driving the Monte the other day and turn the radio on (aftermarket connected to the stock radio power wire). The radio turns on, but there is no sound. I try everything with the settings, CD, etc... no sound. So I drive back home and pull into the garage. Mess with everything again... no sound. I leave the key on and open the door to prepare to crawl under the dash- boom! Sound! Scared the crap out of me cause I had the volume turned way up. Close the door- no sound. Open the door- sound. Push the dome light switch in... I still have sound. ???? Close the door, no sound. Open the door- sound. The door does not have anything electrical going to it- no power windows, locks, or mirrors. [censored]?? I do this a couple more times and I'm sure I had a stupid look on my face. I look at the dome light- it goes off when the door closes (no sound) AND when I push the button in (sound). For no good reason, I pop the cover off, grab the bulb and give it a twist... and burn the crap out of my fingers. Owww! And boom! Sound with the door closed!!! [censored]?????? My car is haunted?

My 70 came with a console and it even had the door attached. The door is cracked and missing pieces, so I removed it and just left the console open. Those doors make me nuts because how cheap they feel- the two halves rub together and make that annoying plastic squeak. I never really intended to replace it, but I got tired of looking at and listening to the junk I store banging around in the console. I dug the door back out and installed it, and when I leaned on it with my elbow while driving- squeak! So, I came up with a cure. I sprayed "Great Stuff" spray foam (blue can) between the two halves. Amazing the difference! No squeak, and the door has a little weight to it now so it doesn't feel cheap! I am going to get a repop door and do the same thing. Of course, after thinking about this some more, I'm going to stuff the repop with some dense packaging foam before going to the foam spray!

I'm kind of obsessive when it comes to little noises, taps and squeaks. Trying to chase them in a 40+ year old car is a challenge! A couple of weeks ago I dropped a new motor into the Monte (long story) and the weather finally let me get some seat time this weekend. The thing runs great but there was this weird rattle or whistle coming from what seemed to be the carb. It would go away when I put my hand over the throat of the carb- of course it would try to stall at the same time. I kept driving it and the rattle changed a little- but the "whistle" was still there. I then took a closer look under car and found a 1/2" pipe plug I had dropped laying on the header tubes. Somehow this plug was causing a weird resonation back through the carb. I have found rocks, hardware, tools, etc. on headers before, but none that made that sort of bizarre noise. Now I'm off to find the 14 other little squeaks and rattles!

Thanks! The voltmeter was a direct bolt in, and I don't think I had to modify much for the oil pressure gauge. The oil pressure gauge is mechanical, and the gauge mechanism makes it impossible to install the cluster light. I used electrical tape to cover the opening on the circuit board. There is a light with a white plastic base (different than the black base lights) in the hole behind the temp gauge, and that lights both gauges more than adequately. And yes, those screws are plastic- nylon actually- and yes they prevent grounding out. If you install a voltmeter from a chevy truck, the top lug is ground and the left one is 12V+.

Hi all- many years ago I took my stock cluster and replaced the amp gauge with a voltmeter, replaced the fuel gauge with an oil pressure gauge and replaced the clock with a big fuel gauge. The stock cluster had the amp gauge, tach, speedo, big clock, temp gauge and small gas gauge. The donor gauges were from a 78 Suburban. Someone asked me if I could detail what I did, but I had already installed the cluster and didn't have any pictures. Today I removed the cluster again (dang that isn't easy!) to replace the Suburban gas gauge with a big gauge from a 70-72 Monte that I got on ebay. Here is the completed cluster (I am going to replace the lens for the entire cluster before I put it back in). This is the voltmeter- I bolted the gauge to the same spot as the amp gauge. I did not use the connections on the circuit board- I ran a hot wire from the engine compartment and a local ground. I taped over the amp gauge connections on the circuit board. I removed the stock gas gauge and replaced it with the oil pressure gauge. To connect the new gas gauge, I ran wires from the circuit board connection points to the relocated spot. I made the connections on the circuit board using nylon hardware to keep them from grounding out on anything. Mounting the gas gauge was the most work- this Monte gas gauge was originally mounted on the left where my tach is (different cluster option). To mount it on the right where the clock was, I used the clock’s plate that held the clock and the lights. I cut the gas gauge’s three-hole mounting pad out of the plate that came with the gauge and tacked it to the clock plate. I had to get the angle right! The right and left gauges are tilted in slightly. If you don’t want to look for a donor Suburban, I just stumbled on the Tachman (http://www.tachman.com/gm.htm) who is doing the voltmeter or oil pressure conversion into the amp gauge spot. I haven’t seen anyone do the conversions I did, but I now have all of the engine info I want in a stock appearing form!

I ended up using this connector- spliced the water pump end off of another stock hose. Be Cool suggested a lower hose from a big block pick up but that didn't work. And I couldn't get Pace Car Jeff to make me a custom hose! This works- life is good!

2X thumbs up on the Morris mirrors AND the 3-point belts!!