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Another A/C problem thread

I think it was 45psi low at idle, but he said 50. 4.0 pounds is right off the old accumulator, GM factory sticker. He has a digital scale, whatched it with my own eyeballs!

We have 2 temp pyros- one digital one dial indicator, alternating between all vents, doors closed, stationary and driving.

Recirc light does not come on... ever... and it isn't physically coming on either (can't hear the loud rush of air you normally hear with it selected/pressed on).
 
Could try putting vise grips on the heater hoses and see if the heat door isn't shutting. Is the compressor running fairly consistently or engaging and disengaging alot ??
 
on several occasions the A/C light would go out and I'd have to push it, push it again, and again over a 5 minute period. It finally stayed on by itself.

When I was under the hood, the A/C clutch stayed engaged...

???
 
Steve93mustanglx said:
I think it was 45psi low at idle, but he said 50. 4.0 pounds is right off the old accumulator, GM factory sticker. He has a digital scale, whatched it with my own eyeballs!

We have 2 temp pyros- one digital one dial indicator, alternating between all vents, doors closed, stationary and driving.

Recirc light does not come on... ever... and it isn't physically coming on either (can't hear the loud rush of air you normally hear with it selected/pressed on).
Click to expand...


In my GM manual 3# was what was required for 98 burb, I wonder if 4# was too much and the lowered to 3#, what kind of compressor is on the 95 ? Maybe that is the difference ?
 
High low side "Usually" is overcharge. It won't cool worth a crap if it's overcharged but 4#'s is belivable in a burb. I forgot what I put in mine actually. I would still try clmping the heater hoses. It's an easy test and will tell you if the heat door is closing. If not the a/c will have a very hard time overcoming the heater.
 
3# for the 98 burb, and 2# for the 98 truck, I've had to do both in last 2 years, lost evaporator on the truck that job plan sux, and the compressor on the burb, but those use the long compressor on driver side IIRC the 95 uses the short round one on passenger side.

BTW Kenny my FSD made it back to me yesterday :thumbsup:
 
Acesneights1 said:
Could try putting vise grips on the heater hoses and see if the heat door isn't shutting. Is the compressor running fairly consistently or engaging and disengaging alot ??
Click to expand...

This is a good idea!

Steve93mustanglx said:
on several occasions the A/C light would go out and I'd have to push it, push it again, and again over a 5 minute period. It finally stayed on by itself.

When I was under the hood, the A/C clutch stayed engaged...

???
Click to expand...

Your control head has issues, may need to replace it. Again common failure on 1995's and were only used in 1995 - you now know why!

Possible the high pressure switch is tripping and shutting off the AC light along with the compressor. I did not say it was tripping accurately. Switch is in the back of the compressor.

Turbine Doc said:
In my GM manual 3# was what was required for 98 burb, I wonder if 4# was too much and the lowered to 3#, what kind of compressor is on the 95 ? Maybe that is the difference ?
Click to expand...

Sticker on AC parts for that year is gospel. GM dealer TSB or book may have a revised 134a amount. The 1995 systems have the old R-12 design compressors converted/adapted to R 134a on the passenger side. 1998 would be the new and better design compressors.

Look at your pressures and the temperature of the 134A. You will be lucky to get 50 degrees at idle. However you are 10 degrees hotter on the air than the R134a is. I recall 1995 may have had a heater coolant bypass valve and vac controlled on 350 gas - unknown if diesels had this. Look for a valve by the firewall in the heater hoses. 220-250 is 137-146 degrees on the condenser. Without airflow from the engine fan the cold side is affected by this.

40 PSI low side at higher RPM's is about to cycle the clutch to prevent iceing the evaporator. Other than possibly a worn or internally leaking compressor or expansion valve issues I think your AC system is ok. Troubleshoot the control head and likely replace it. Here the dealer's shop can help you as the labor isn't much over the cost of the HVAC control head part and they can return it if it is not the problem while still in the shop. Pinching the heater hoses closed as said above will point you in the proper direction.

http://www.csgnetwork.com/r134apresstempconv.html

EDIT: Pull and check the HVAC controls and all other fuses for corrosion just in case...
 
Thanks for all the tips. I will dig in to this over the weekend. Too bloody hot right now, and thankfully I am getting quite a few hits on the resume the past week or so, and its keeping me busy. This 18 month unemployment thing is really old - wish me luck!
 
My 96 burb says it takes 4# of R134a also. If i remember right the correct low side pressure is 33PSI and that should be at or close to 2,000 rpm. Granted that pressure will be a little higher or a little lower depending on the ambient temp but somewhere around 33-35 is probably right. I am having AC problems on my truck too but until i get the money to do all the work i want to do i am just leaving it alone. I am sure my truck has too much oil in the system and that is part of my problem. The other part is the leaking compressor to hose o-ring and probably partly blocked orifice tube.
 
Warwagon- good call. Temps finally under 100 today so I ventured out to the driveway to look for these issues. I grabbed the blower motor connector and it would go in and out on the high fan setting. The pics tell the tale. I cut it out and used insulated spade connectors, slightly staggered, to replace it.

As suggested I also replaced the blower motor. I was able to plug the factory ground back up- I previously had a jumper ground cable on the old setup.

So, fixed a bad ground and bad connector. Fan blows on high at my command now! Suweet!

Recirc... that still ain't working. I'm happy though- and thanks for all the help.

Any suggestions on the recirc?
 

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Not going into recurc is the control head. You have the full left turn on the temp and the button that will put it in that mode. INOP = replace POS control head.

Recirc was the same issue Acesneights1 had opening and closing by itself - My case was a bad door motor control unit. You could push it open... Vehicle at speed would suck it open. But the light would go on so not the control head for 'us'.

I would double ground that blower motor... Use a second wire and ground it in the cab from a different blower motor bolt. Not required but you know grounds...
 
ug... yay. At least its easy to get to compared to the motor on the door. Gonna look for one online tonight. Is it true there are 2 p/n's for 95s?? Is there a place you recommend to pick one of these up?
 
Bought replacement control head from Rock Auto. Works like a champ and $160ish shipped (with a discount code). They must have redesigned it- it looks different on the back.

It's 70 degrees out right now (at 7am) and it's pushing 46 degrees after only a minute or 2 at idle. MUCH better than before. Can't wait til this afternoon when it's hot to see how it feels!

Thanks a bunch for the assist!
 
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