Automotive Air Conditioning Information Forum (Archives)

Superjjmj on Tue May 06, 2014 6:15 PM

Year: 1984
Make: Chevrolet
Model: C10 silverado
Engine Size: 350sb
Refrigerant Type: 134a
Ambient Temp: 87
Pressure Low: 51 psi
Country of Origin: United States

Hey guys just bough my first truck! It has what i belive to be all new components lines compressor etc. the problem I'm having is the compressor is engagaging sometimes (about 2-3 times in a row) then I have to push the peice that normally clicks in by its self by hand any idea ? Even when it is engaged though it's still not blowing cold I plan on putting a manual on off valve for my heater core under the hood cause it still reeds like 100 (85 outside)in the cab ? It's an r4 compressor(I belive) is there anyway to fix this problem or will it need to be replaced ? Whenever I get the on off valve for heater core I will let you know if its getting cold I gotta feeling ghe heat is still on even when I turn it off and that's why it's not getting cold but either way the compressor should engage and stay engaged? I'm jumping right to the battery

Dougflas on Tue May 06, 2014 6:44 PM

leave the doors open. What is the high side reading?If I am reading correctly, you have to push on the front of the clutch for rngagement? Your clutch plate spacing is too wide or clutch is worn out. You may have a poor functioning condenser or fan. Must have high side readings.

Superjjmj on Tue May 06, 2014 7:09 PM

Sorry I'm only 15 I'm only going off what the cans telling me how exactly do I adjust the clutch spacing ? Once the clutch is in engaging I planed on bringing it to my friends and evacuating ,leak testing and refilling ? I just want to make sure everything's working before I spend money on freon but I will try and get you the high side reading if I can what do you mean leave the doors open? And yes somtimes the clutch will click in mostly I have to push it in my self Even when the compressors engaged it's not blowing cold I think the heat hate valve isn't shutting all the way that's why I'm going to put a manual one on it any suggestions on what I need and how to adjust the plate spacing would be great

Before I bring it somewhere to get fixed I'm going to try the heat valve and see if it blows out cold and then if it does I should adjust the plate spacing? I bought the truck from a buddy he said the ac worked new lines new everything but we couldn't get the ac belt to line up the night I bought it so that's how I got to where I am now is there an easy way to check other components ?

mk378 on Tue May 06, 2014 7:20 PM

GM clutch plate installer -- There is a special tool that screws into the clutch hub to adjust the spacing. There are 2 versions of the tool, I think on a 1984 model (assuming compressor is original) you would use the old style one with SAE threads. Newer compressors have metric threads (As lousy as the R4 is, they made a heck of a lot of them). The plate is a press fit on the shaft, the special tools are necessary to smoothly force it on and off. If you try some other way you are likely to damage the compressor.

And like Dougflas said, you need a real manifold with 2 gagues so you can see the high side pressure to be able to diagnose the refrigeration system. If you keep charging without seeing the high side, it is likely to go up too high and you won't know until the relief valve pops (if it has one) or a hose blows.

Worn out fan clutches are real common on old trucks, the fan still turns fast enough that the radiator and engine doesn't overheat, but it takes a lot more air for the A/C to work well. Also after a few generations of owners, it's common for the plastic shrouds around the fan to be gone. Those are important to actually suck air through the condenser rather than just stir it up behind the radiator.

Edited: Tue May 06, 2014 at 7:31 PM by mk378

Superjjmj on Tue May 06, 2014 8:15 PM

I under stand its not going to work perfect I'm going to check and see if it does blow out halfway cold whenever I get the heater core valve and if so I will get that tool (can they be rented from a local auto parts store?) and what should it be gapped to I guess I should use feeler gauges if you could give me a rough estimate that be great. Thanks guys this fourm is very helpful !!


Edited: Tue May 06, 2014 at 8:15 PM by Superjjmj

mk378 on Tue May 06, 2014 9:12 PM

Instead of a valve, you can just disconnect the heater core and use a loop of hose between the two places on the engine. This is important on some systems that counted on constant flow through the heater core to avoid hot spots in the engine before the thermostat opens. Also put a loop of hose on the empty core fittings to keep bugs and dirt out so you can easily put it back in service next winter.

As far as gap, you just need it closer than it is now so you get reliable engagement. It is hard to use feeler gauges on a used clutch because the surfaces don't stay flat as they wear down. As close as you want, yet does not drag when it is off, is acceptable.

Edited: Tue May 06, 2014 at 9:14 PM by mk378

Superjjmj on Sun May 11, 2014 6:26 PM

Got my valve installed compressor engaged still not cold what should be the next step I should take ?

mk378 on Sun May 11, 2014 6:40 PM

Get both pressures, low side and high side. Use the standard test conditions: controls for max cold, doors open (so the air inside the truck stays at the same temperature during the test), and engine at 1500 rpm.

Superjjmj on Sun May 11, 2014 7:53 PM

What should they be reading?

Dougflas on Sun May 11, 2014 8:54 PM

30 to 35 low side 225 to 250 high side