Need Air Conditioning help 82 vette

[Saltydog]

I have a 82 vette.
I replaced the AC compressor, drier, orifice tube, and had a local Firestone shop to charge my system with 134a. I have determined that my air box doors are all functioning properly including the max air outside door. I have placed a cutoff valve on my heater core hose and shutoff water flow to it.
The AC when placed in Max cool with car running at 55 mph on highway will blow at vent a temperature of 48 degrees, which is ok with me, but when I stop a idle the temperature will increase to 60 degrees. My 88 silverado pickup with 134a gas will put out 40 degrees at vent temp when it is idling.
I am now wondering if placing some sort of relay switch to turn on the electrical radiator fan will help with my problem. It seems as though I need more airflow across the coil as happens when I am traveling at 55 mph.
If some one knows the proceedure for electrically hooking up such a relayed switch please advise me. 10 to 15 degree vent air temps are to much.
Thanks for any help.
Saltydog

 

[bill81vette]

how much r134a did they put into the system??? (as in pounds..should be around 2.5-3.0 lbs.) usually if its not running cool enough it does not have enough refrigant in the system..I would start with that and see what happens.

 

[CQRT]

Saltydog:
Noticed your comment about "airbox doors" . . . our 74 coupe has new compressor, dryer and fully charged system - -I can feel a small bit of cold air through the dash vents while in the garage, but once underway there's scorching hot air blowing on my feet - - am guessing I'm pulling heat off the headers, but am unsure where to look or how to get to these doors.

Can someone please advise ?? It's going to be 111 degrees again here today and driving the old Vette looses a bit of its luster in this kind of heat without serious AC !
Thanks

 

[black_81_vette]

If you charged the system with 134A you only need about 75 to 85 % of the amount of freon you would use when charging with R12 about 2 1/2 cans should be suffice.At any rate running 134a in a once dedicated R12 system is a hit or miss affair did you change the reciever dryer? was the old refrigerant and oil drained and pulled down under vac? actually 60 deg vent temp from that system on 134a at idle is good if the ambient temps are really high. Part of the reason the truck gets better temps is the fact that the a/c system on the truck has better evap placement ect and more surface area on the condensor.The vette a/c system has to live in a cramped and not friendly confines to be super efficient running on 134a

 

[George Black]

RWT: My AC problem was the same as yours: Cold at first, then hot/warm after driving a while. Primary cause was heat from engine compartment entering the passenger compartment and the AC ducting system. I finally got it corrected. See Bob Chadwick's 77 Corvette www page. Click on Ventilation. Excellent photos and discussion. It really helped me get started on the problem. Particularly note Bob's 10 point checklist at the end of the section for reducing heat in the interior. I have done them all. Even the small stuff helps alot: upper hood seal,trans. tunnel foam collar, etc.The Reflectix material is really outstanding in my opinion. You can fix the problem, just have to spend some effort/time. --George

 

[CQRT]

Thanks GEORGE . . .great advice. One thing I've learned from the Board is that our individual problems are rarely unique and there's some real creativity and talent among the members.

Thank you !

 

[wishuwerehere82]

Saltydog,

Check for leaves in between your radiator and A/C condensor.
I had a pile in my '82 when I pulled the radiator that were not visible from the outside. They really cut down the airflow.
Also, if your compressor turns on and off frequently,it may be low on freon. It should stay on for a long time until the airbox gets cold. Generally a 60 degree differential between intake and output air is good.

 

[Saltydog]

Thanks Guys for all the suggestions. I'm gonna try them all. I will tell you all that I
added 12 more oz. of 134 than the shop put in it ran the car down the road. The vent temps took longer to drop to 60 degrees so I came back and reduced the amount in the system to an amount that brought the low pressure side down to 45 pounds. I drove out on the highway and low in behold my vent temps dropped to 48 degrees when I put the blower fan on medium blow the temp dropped to 42 degrees I was supprised and pleased. At this point I feel as though I need to hook up a switch to cut on my aux. electric fan when I turn in my A/C. The reduction in the 3 pounds the shop put in seems to have made a difference. If at idle, in downtown traffic, the car would preform at those temps that would be great, but I have yet to prove that. Well, Thanks guys for any other comments or suggestion, I am headed out to try to work on it some more.
Thanks Saltdog