A/C system 100% new and not working right

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ReddyK
Posts: 3
Joined: Sun May 27, 2018 9:21 pm

A/C system 100% new and not working right

Postby ReddyK » Sun May 27, 2018 9:40 pm

I have an 86 Camaro and have replaced every part of my A/C system with NEW parts except for a rebuilt compressor. The vent temps are are 80 degrees and both high and low side pressures are high. Trying to diagnose I have checked and replaced the orifice tube a couple of times 1 white and 1 blue one. The blue tube gave about 5 psi lower pressures. I blew through all the parts with 134a and didn't find a restriction. I felt like the system might have uncompressible stuff inside like water/air since both pressures were high so I replaced the dryer and orifice tube again and got the same results. I added 28 oz of 134a. Less refrigerant had no better cooling and more resulted in even higher pressures. I have an electric fan and a new radiator also.

Here are my specs.

Label says 2.25 lbs R12 -- I added 80% of 134a 28ozs.
8 ozs PAG 150
Vacuumed for 30 min at 29 mmhg
Heater hose pinched off
Ambient temp 80 degrees
Inside car temp 90 degrees
Ran 10 minutes before taking readings

750 RPM
Low side pressure 48 psi
High side pressure 260 psi
Evaporator exit temp 63 degrees
Condenser inlet temp 130 degrees
Condenser outlet temp 103 degrees
Vent temp 80 degrees

1250 RPM
Low side pressure 34 degrees
High side pressure 305 degrees
Vent temp 75 degrees

1250 RPM Wetted down the condenser
Low side pressure 30 psi
High side pressure 205 psi
Vent temp 90 degrees

Any suggestions would be greatly appreciated. I have been working on this for a week and am about ready to take it to someone else.
Thank you,
Steve
JohnHere
Posts: 105
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate

Re: A/C system 100% new and not working right

Postby JohnHere » Mon May 28, 2018 8:37 am

I wonder about the oil. If the rebuilt compressor was empty of oil and you added 8 ounces of PAG 150, that sounds about right. But if the compressor already had oil in it and you added 8 ounces more, obviously that would've been way too much. Just a thought.
ReddyK
Posts: 3
Joined: Sun May 27, 2018 9:21 pm

Re: A/C system 100% new and not working right

Postby ReddyK » Mon May 28, 2018 9:43 am

Too much oil is a great idea. The ports of the compressor looked dry and I tipped it and nothing ran out so I assumed it was dry. I should of held it upside down to make sure but I didn't. I emailed the compressor rebuilder I bought it from and asked if they added oil or not. I have not gotten a reply.
I did find the re-circulation door was not opening to the recirculation position. It is now open and the vent temp has dropped to 50 degrees.

Here are the new conditions:

Ran for 10 min.
Ambient air temp 74
Inside car temp 74

1250 RPM
low side pressure 28 psi
high side pressure 260 psi
evaporator tube in temp 38 degrees
evaporator tube out temp 36 degrees
condenser tube in temp 192 degrees
condenser tube out temp 120 degrees

I know it is cooler today and getting the recirculation door open made a big change. I still feel like the pressures are too high and the inside temp is not low enough. I think I will try to adjust the refrigerant level down first and see if I get any major change.
Thank you all for your help,
Steve
User avatar
Cusser
Posts: 361
Joined: Sun Apr 24, 2016 6:29 am

Re: A/C system 100% new and not working right

Postby Cusser » Mon May 28, 2018 1:09 pm

ReddyK wrote:I did find the re-circulation door was not opening to the recirculation position. It is now open and the vent temp has dropped to 50 degrees.

1250 RPM
low side pressure 28 psi
high side pressure 260 psi


Your pressures don't look too bad. Your 50 degrees - I assume that's while parked and running 1250 rpm. That should get lower in actual driving, do a driving test. Radio show mechanic here with a shop says 55 degrees and lower is OK. And remember: you did a conversion, not R-12 any more.
JohnHere
Posts: 105
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate

Re: A/C system 100% new and not working right

Postby JohnHere » Mon May 28, 2018 1:55 pm

I agree with Cusser. Your system was designed to work with R12. Converting to R134a is always somewhat of a compromise. I wondered, too, whether you replaced the original tube-and-fin condenser with a more efficient parallel-flow condenser. If not, doing so might help it cool a little better with R134a.
ReddyK
Posts: 3
Joined: Sun May 27, 2018 9:21 pm

Re: A/C system 100% new and not working right

Postby ReddyK » Mon May 28, 2018 9:30 pm

Driving it this afternoon the lowest vent temp was 40 degrees. That would be great if it was 90 outside but today was 75. I think that is just OK. I will see what it is like on a hot day. The condenser looks parallel flow.
IMG_3991.JPG
IMG_3991.JPG (144.02 KiB) Viewed 418 times


I scrounged up a vacuum diagram and will make sure all the vent and recirculate doors are working properly. I will try driving for a few days and see how it performs and report back.
Thank you for your help,
Steve
JohnHere
Posts: 105
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate

Re: A/C system 100% new and not working right

Postby JohnHere » Wed May 30, 2018 5:48 pm

Yes, looks like a parallel-flow condenser to me, too. Good!
Upthread, you mentioned that the HP dropped quite a bit when spraying the condenser with water, suggesting insufficient airflow across the condenser. Since you installed a new electric fan and we assume that it's working as it should, double-check to ensure that air is actually going through the condenser, not around it. No plastic bags or other debris blocking airflow, shrouds in place, and foam gasketing installed between the condenser and radiator.
71403
Posts: 39
Joined: Fri May 27, 2016 12:46 pm

Re: A/C system 100% new and not working right

Postby 71403 » Wed May 30, 2018 7:35 pm

Electric fans on those cars (3rd gen f-body) are barely ok at best. Was common "back in the day" to upgrade them when increasing engine performance to keep things cool. 4th gen fans were are near drop in IIRC.

Dropping 100psi wetting down condenser suggests not enough airflow, with this much age on high current electrical connections make sure both fan motors are getting full battery voltage when running.

Condenser in pic looks like Piccolo header type not PF. Site sponsor may know but I don't recall a drop in PF for these cars.

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