dp2boy

OK after buying a cheap thermometer my readings are (with 28 psi on the low side): ambient temp is 84F and center vent temp is 59-60F. So my subjective "hand in front of the vent" test was correct, something isn't quite right.

Ron

Joel,

It might be helpful if you could hook up a set of gauges to the low and high side and see what they say. At 2K rpms knowing ambient temp you can figure what the pressures should be. And then hopefully you will be in the right range for your vent temps.

You could hook up a valve to the yellow hose and I think you could use that to release refrigerant in a controlled manner, hopefully someone else will chime in here and confirm this. That way you can bring down your low pressure slow enough to see what's happening. Remember to give the system a chance to settle in every time you release a little gas because the pressure reading will not change the very second you release some refrigerant.

Also why did you have your compressor changed? And did they put in a new receiver/dryer and expansion valve too? Was oil added when the compressor was replaced and if so how much? (Maybe no oil was added at all because lots of times compressors come with a full charge of oil for the system they are designed for.)

dp2boy

I think I'll take it to a shop that specializes in A/C and have them charge it correctly. I changed the compressor because it was really starting to groan and rumble when engaged. Almost everyone that heard it said it was consistent with a pump going bad. I'll have to say that I no longer hear the goaning sound but as you can see the system still isn't cooling properly. I'll post after I get it checked out. Thanks for your help so far.

bangal911

Could you please specify if you had this great 48 F with a R12 or a R134a coolant?

What was the External temprature? In Lebanon (Middle East) it varies from 95 to 104 F (35 C to 40 C)

I wonder how 993 in Arabic countries do when Temp reaches about 113 F to easily more than 122 in august.

Thank You
Naji

Ron

Naji,

Last month I decided to try to reduce my A/C center vent temp a little. Car is a 1997 with R134a.

I was trying to get my vent temps as low as possible. I added gas until my high pressure reading was 290 psi at which point I added no more gas. Low pressure was 14 psi with 86 degrees ambient which produced a center vent temperature of 48 degrees.

My factory workshop manual has graphs and ranges for each of the values. At 86 degrees ambient they are as follows:
low pressure--10.5 psi to 16.5 psi
high pressure--218psi to 290 psi
vent temperature-- between 43 degrees and 50 degrees

I added .22 lbs of gas which I think is about 3.5 ounces. I have a refrigerant scale so I know that is how much I put in. My vent temperature was peviously 52 degrees so I improved it a little. I'm satisfied with the vent temp. so I did not mess with it any further.

I suspect the ambient was a little higher, but I did not put the thermometer 2" in front of the condensor as I do on other cars. Also the high pressure may go down some with more air flow, i.e. car moving although the A/C fan was running. On other cars I'll put an electric fan to blow on the condensor when I'm filling.

While it gets into the 100 degree F temperatures where I live with horrible humidity it does not get in the 113 to 122 that I can recall.

Felix

Naji,

At 35 C your vent temps should be between 9 and 13; at 40 they should be between 12 and approximately 16.

deltawedge

If it was mentioned before, please forgive me, but all testing of pressures for the AC need to be performed at 2000rpm with AC on max cool and fan on 4 (system running for ~10 minutes). At idle with the compressor engaged readings of 30-60 psi on the low side are typical. At 2000rpm, the low side pressure will be lower (10-20psi) and the high side will be higher (220-290psi), based upon outside air temp. Hope this helps!

Jean

Naji,
Welcome to Rennlist.

We sweat! If the car has been sitting under the sun for a couple of hours, you will need another hour of driving at speeds to get some cool air. Should not forget that the inside temperatures are much higher than that when the car is sitting outside.

micnicholas

Alright, been doing some research, Electrical is not my specialty and am still fishing for leads.
95 C2. blows semi cool, far from cold. It's been crappy for a while but I don't drive it much but I'm making some big changes in my world so Im trying to shake down all of my loose ends and get this car 100%.

I evacuated the system and pulled a vaccum, held without a leak. Installed a new dryer but still warm thinking that thing is shot being 15 years old. Compressor kicks on for a little while but kicks off after a minute or 2. I'm assuming system knows the fan isn't working is why it kicks off? Put 29oz. of 134 in. Condensor fan still doesn't work on any setting/speed. It's plugged in, swapped fan relays with no change.

Speculation points at a balast resistor but I don't really follow the electrical talk so well. Could be a bad fan motor too. Any ideas from you more experienced fan-atics out there? thanks a lot!

Marco8

See: https://rennlist.com/forums/993-foru...diagnosis.html
Good Luck