[JLonano]

About a year and a half ago I got my factory AC working via a new blower motor and fresh charge of R12 in my 67 GTO. The A/C blows quite cold but output is kinda low.

My question is the force of air that should be comming out of the vents. It seems a bit low (kinda like a low setting of 2 on a modern A/C). It this the way the factory intended it or should this system be a wind tunnel at "4"? All the fan speed switches work and change the speed of the fan. I checked the for leaks ducting and it is "seems" OK. Any tips from A/C car owners?

[JLonano]

About a year and a half ago I got my factory AC working via a new blower motor and fresh charge of R12 in my 67 GTO. The A/C blows quite cold but output is kinda low.

My question is the force of air that should be comming out of the vents. It seems a bit low (kinda like a low setting of 2 on a modern A/C). It this the way the factory intended it or should this system be a wind tunnel at "4"? All the fan speed switches work and change the speed of the fan. I checked the for leaks ducting and it is "seems" OK. Any tips from A/C car owners?

[goatbuddy67]

James, I asked my mechanic the same question last week on my 67. He pointed out the 4-prong plug on the harness on the right firewall at the blower and explained that you move the plug over and change positions,from left to right,to go from low output to high output. The plug is mounted vertically. I have yet to prove this theory,because I have other issues with my a/c,heater not operational yet. Let me know.Thanks
Buddy

[JLonano]

Buddy,

I see the plug mounted to a natural metal cap-bracket screwed to the flat firewall surface. This is just to the right of the blower motor like you explained. I'm not following your instructions. I do not see how this portion of the harness will plug in any other way. Tell me more and I'll give it a shot.

While you are sorting out your A/C, perhaps we could help each other out. I 'm still having trouble getting my defroster air valve and much of the vacuum stuff right. Right now, my A/C is in recycle most all of the time. The heater works. Of course, the a/c guy I paid money to sort it out for me did not want to touch it with a 10 foot pole.

James

[ May 23, 2002, 09:06 PM: Message edited by: James Lonano ]

[TheTempest]

Jim,

I believe what is being talked about here is the resistor block that is used to control the speed of the fan motor. It's kinda crude in operation: basically you're taking the 12v of the car electrical system and running it thru a resistor in series with the blower motor. The bigger the resistor, the bigger the voltage drop across it and the slower the blower motor will run. Since the resistor turns "wasted" voltage into heat, the resistor block hangs down into the inlet airstream of the HVAC system to cool the resistors so they don't burn up. The resistor block is located on the top of the HVAC air intake plenum. There will be a dual diaphragm valve w/2 vac lines on the side of the plenum (near the dist), move to the left and you'll find the resistor block; it will have a flat electrical plug connected to it. You can see if the resistors are all intact by removing the flat electrical plug and removing the 2 sheetmetal screws that hold the resistor block to the top of the plenum.

Another reason your flow rate is low might be the damper doors inside the HVAC plenum under the dash are stuck and/or the vacuum motors used to operate them are shot. Also, the dual diaphragm valve (in the engine bay) might also be toast, although I think the only function of this is to select outside air or the recirc mode. There are foam rubber gaskets that seal the internal damper doors; after 30 years you can bet the foam rubber has turned to dust. Also the vac lines themselves are probably pretty dried out and leaky. The best way to check out and restore your underdash system is to remove it completely from the car, which can be a booger to do but is *not* impossible. I did mine and one of the previous owners made it much "easier" by trashing some mounting studs and a bit of the flange. There is a muli-port rubber plug that is part of the dash control panel; it routes engine vacuum to the appropriate vac motor (there are 2 attatched to the under-dash plenum plus the dual one in the engine bay) to operate the system in the selected mode (def/heat/recirc/etc). I don't have the unit in front of me, but I marked all my vac lines and can give you the proper routing for the ones coming off of the multi-plug. The main vac source, at least on a 2bbl 326, comes off the carb fitting shared with the vacuum modulator line to the tranny. Sorry to get so wordy but I hope some of this info I've discovered by rebuilding my system can help you out. Have a good weekend and feel free to e-mail me with any questions.....I can even send you photos of my stuff if you want.

Mike

[JLonano]

Mike,

My goal about a year and a half ago was simply to get the A/C blowing cold air but as you know from doing yours, some of the vacuum stuff can get pretty complicated! DOn't worry about being too "wordy"...I love the details you described.

Resistor block:
I am aware of the resistor block on top the plenum. Actually it was one of the first things I checked. I spread out the "resistor" wire as it was touching in a few areas. I'm wondering if I should try bypassing the resistor and running a wire to wire hookup in the plug as for experimentaion purposes. Otherwise, I did not measure the resistance across the coiled wire but it may be sapping too much of the voltage to the blower motor as you pointed out. I am wondering is soldering a ceramic resistor would be the right move here. Any idea of the value of this resistors?

Vacuum Stuff:
Otherwise, my underhood Vacuum modulator is good but the arm that attaches to the flapper door under the cowl vent is missing. Of course this keeps the A/c in recycle mode which is not a bad thing. I'm not too sure if the 2 vacuum lines I have hooked up to it are correct. The second vacuum modulator for the defrost flap is not working either. Any more Vacuum modulators I am not aware of? Otherwise, it would be a good case of trial and error to figure out the complex vacuum routing. I can get to the vacuum distribution block with the glove box door removed.

Air leaks:
With the car running, A/C on, and cowl grill removed, I can feel some cold air leaking up from the lower passenger side cowl-inner fender area trickling out.

Any tips would be GREATLY appreciated.

Thanks,

James

[ May 26, 2002, 07:47 AM: Message edited by: James Lonano ]

[TheTempest]

Originally posted by James Lonano:
Mike,

My goal about a year and a half ago was simply to get the A/C blowing cold air but as you know from doing yours, some of the vacuum stuff can get pretty complicated! DOn't worry about being too "wordy"...I love the details you described.

Resistor block:
I am aware of the resistor block on top the plenum. Actually it was one of the first things I checked. I spread out the "resistor" wire as it was touching in a few areas. I'm wondering if I should try bypassing the resistor and running a wire to wire hookup in the plug as for experimentaion purposes. Otherwise, I did not measure the resistance across the coiled wire but it may be sapping too much of the voltage to the blower motor as you pointed out. I am wondering is soldering a ceramic resistor would be the right move here. Any idea of the value of this resistors?

**The "high" setting on the control panel should give you full voltage to the blower motor; it is the 3 thru 1 settings that use the resistor block to drop the voltage to the motor. I would be very careful about bending the resistor wires; these blocks are a bit hard to come by so treat them with "kid gloves". If you plan to keep the A/c functional then getting a spare resistor block would be a nice insurance policy; I don't think they are available new anymore. If you have a multi-tester, I would check to make sure you're getting 12v into the resistor block and to the motor on the highest setting.

Vacuum Stuff:
Otherwise, my underhood Vacuum modulator is good but the arm that attaches to the flapper door under the cowl vent is missing. Of course this keeps the A/c in recycle mode which is not a bad thing. I'm not too sure if the 2 vacuum lines I have hooked up to it are correct. The second vacuum modulator for the defrost flap is not working either. Any more Vacuum modulators I am not aware of? Otherwise, it would be a good case of trial and error to figure out the complex vacuum routing. I can get to the vacuum distribution block with the glove box door removed.

**I think there is only one vac motor inside the car...I'll have to look at mine 'cause I can't remember for sure.

Air leaks:
With the car running, A/C on, and cowl grill removed, I can feel some cold air leaking up from the lower passenger side cowl-inner fender area trickling out.

**Another place where you may be loosing air is in the right fender area; this is where the condensor lives. This is also where the cold air is blown into the underdash manifold (through what would be the fresh air footwell vent on a non-A/C car). In my car, one of the previous owners tore into the HVAC system and failed to reinstall any of the seals (which by now would be pretty worthless). In their stead was used GOBS of dum-dum to try to create a seal or nothing at all (which has greatly reduced the "water proof-ness" of the car)

Any tips would be GREATLY appreciated.

**By itself, a small air leak or two isn't going to cause too much loss of A/C performance. But combine leaky ducting with some dampers that don't function like they used to and possibly a lower than normal voltage and you've got enough stacked against you to have a weak system.

Thanks,

James

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[JLonano]

Mike,

Thank You VERY much for the thoughts and insight. You have given me the shot in the arm to check out the things you outlined in the previous post. Time to get the meter out and check some of the voltages. Best yet, I'll get with Bethels Goat Farm and try and source a spare resistor block.

My schematics show only the fresh air and defroster vacuum modulator. Otherwise, I made great progress sorting out the vacuum lines today and should hopefully have it done soon. Some black RTV was used to plug up some leaks in the underhood ducting which upped the output a bit. I'll rig up a rod for the fresh air-recirculate flap and take it from there. I also took the interior out and finally installed "modern" undercarpet insulation to keep the heat from the headers out of the passenger compartment as well as under and behind the rear seat. Should help some I think.

James

[karl emerick]

all good advice. thanks for the info fellers.

james,
I think I made extra 'arms' when I redid my 67 A/C. if you need one email me off list.

[dallas]

You may have to go a little further into the system. I had a low airflow problem with my '66 Grand Prix. After checking all the typical stuff, I discovered the heater core was plugged with dirt, hair, and other debris. I replaced it and the air flow was fine.

It's a pain in the neck to get out, but the replacement was only about $40-45. I think mine came out from the front of the firewall, but the nuts had to be removed from under the dash (in addition to the outside casing nuts/bolts).

Good luck!

[trshman]

I have the exact same problem James and was going to post the question when I found you had. What luck. I've got a '66, I don't know how much of a difference that makes but figured I'd mention it.

I got my car a year ago January. Except for a small leak that was easy to fix the air worked from the day I got her and blows real cold but like you say output is equal to about a #2 on a modern car.

I have 2 other problems maybe you all can help with, the center vent doesn't have much influence on directing the output. The air seems to mostly come from top of the vent opening rather than through the vent itself.

Also the vent doesn't hold it's position. I've got a cover from a book of matches shimmed in there temporarily.

Thanks again. As soon as I get my car out of the paint shop trying your suggestions will be at the top of my list.

Have a good one,
Bob G.

[TheTempest]

Jim,

Good ideas from the other guys about the heater core being plugged...amazing what crud can collect after 30 plus years. Also, I find that 30 plus year old "permanently lubricated" bearings are anything but. If you're so inclined and feeling adventursome, you might consider opening up the blower motor to try and get to the bearings so they might get a fresh shot of lube oil (after you clean the solidified crud that was once lubricant off of the shaft end). This is kinda tricky stuff, this last option, and if you're not careful you *can* turn the blower motor into junk...but if you take your time and proceed *very* carefully you can make some improvements. Sounds like you're on the right track....good luck with your efforts.

[JLonano]

RG,

Sounds like we are in the same boat my friend! I don't think there is any difference between the '66 and '67 A/C units.

After I replaced the blower motor, LOTS of leaf's, sand, and crud "blew" out from the vents for 2-3 weeks of use. There is still some left in there giving alot of weight to the heater core being partially blocked. I hear a heater core replacement on these cars is torture.

The main question is how hard should these older units blow "factory new". Is this typical of the era? Most GTO's at the shows don't have working factory air or have a replacement vintage air unit.

Otherwise, your center vent may not be aligned properly to the duct. The solution is a pain having to remove the ash tray to loosen the a/c control unit speed nutz(!), reposition and retighten. I use the matchbook trick too....my vent is very floppy.

In Florida is is very hot right now. The modern dynamat style insulation under the carpet and rear seat has done wonders for the a/c's efficiency. Like everything else on these cars, it is one more thing to obsess over, tinker, and generally tweek for years on end!

When you get your car back, we should get together and meet halfway. I live in Jupiter....about 50 miles north of you. We could meet in Delray Beach or something. Hold on to my e-mail fl_799@yahoo.com Always nice to meet people from this forum (and drool over the cars too!)

James

[ June 06, 2002, 12:14 AM: Message edited by: James Lonano ]

[trshman]

James,
Absolutely we should get together. Love to meet you and see your car. I used to travel to Stuart 3 times a week from Miami so Jupiter's no problem.

I actually owned a couple of new Pontiacs from '61 to '64 as a kid (selling land over the phones and making more money than I knew what to do with ) and can tell you the a/c blew cold and hard, no hot start problems, no excessive operating temperatures. I don't know what the hell happened but none of these things were issues then but I think that the comments about stuff accumulating over 30 years is probably the answer. The 2 previous owners of my car were Vegas residents and I can see the sand and grit in the instruments and every electrical connection I open. In fact every time I pull a connection apart to clean it a problem I had either improves or disappears. Eventually I'll get to everything but that's probably the answer to a lot of these problems [img]smile.gif[/img]

Have a good one and I'll let you know when my car's ready to roll.

Bob G.

[dallas]

Mudhen;

You are 100% correct about the fan motors. As I recall, the fans were never as strong as they are today, but the grease turning to "gum" can really slow 'em down.

I have a '87 Lincoln Town Car that gets daily use whether it's 30 degrees or 120. The fan has always blown well, but it quit one day a while back. I pulled it out (much simpler than the '66 Grand Prix), cleaned the resistor, and cleaned and re-oiled everything I could see on the fan motor and its squirrel cage. When I hooked the power to it, it jumped out of my hand from the torque. I reinstalled it and the sucker blows hard enough that people in the back seat complain it's too cold.

Yup, that 30-year-old grease doesn't stay "greasy" forever.

IT is a pain-in-the-rear job, but it's well worth it! Heater core is approx. $45. Plan on 4 hours labor with a helper. Lots of nuts to get from under the dash, plus the case has to be opened from under the hood. Get a buddy who's double-jointed, a case of beer, and take your time. Oh yeah, write down where each stupid nut and screw goes!!!!!!