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Working on my wife’s 99 6 speed “hatchback” and I’m flustered. I replaced the orifice tube, drier and several seals last fall, best I could get out of the vents at Max cold, recirculate is 50 degree air, the low side pressure Was 35psi Low side, and high side 250psi on an 80 degree day. I decided to tackle it today 80 degrees ambient, no refrigerant loss since last year, same pressure same outlet temperature in the coldest vent. It does not have dual zone climate control. Where to start checking for a restriction? Are there line temperature differentials I can reference before I start throwing parts at it? It has gotten maybe 100 miles since I did the work last fall.
Thanks in advance,
Chip.
Have you thoroughly cleaned out the condenser and radiator fins? I had to take my fans out to replace the motors. You would be amazed at the amount of crap that collects in the fins. Air flow over the condenser does have an impact on cooling ability.
Have you thoroughly cleaned out the condenser and radiator fins? I had to take my fans out to replace the motors. You would be amazed at the amount of crap that collects in the fins. Air flow over the condenser does have an impact on cooling ability.
Thanks Ed, I didn’t even think to check that out since it has a cover over all of it. That will be my project first thing in the morning.
I made an air wand out of one of those really long air nozzles that are under 10$ at places like Northern tool. I crimped the end shut and drilled a few small holes in it - really worked well.
...best I could get out of the vents at Max cold, recirculate is 50 degree air, the low side pressure Was 35psi Low side, and high side 250psi on an 80 degree day...
Pressures vary not only with temperature, but with humidity and the RPMs of the engine, and without the last 2 parameters it's impossible to tell if your readings are normal or not.
A ∆T=30°F doesn't seem bad, but I suggest you retake your readings following the procedure summarized below and report back.
Take a look at this Post. It has detailed instructions to check/add refrigerant.
-These are the CliffsNotes:
First you'll need to find the current ambient temperature and humidity. Then, using the chart below, determine your target values for:
High Pressure
Low Pressure and
Center Vent Temp.
Now proceed to take your readings. Make sure you take them with (otherwise readings will be affected):
I made an air wand out of one of those really long air nozzles that are under 10$ at places like Northern tool. I crimped the end shut and drilled a few small holes in it - really worked well.
Looks like tomorrow I’m hitting Horrible Freight for a long nozzle blow gun. I removed the cover, hit it with compressed air and blew out a mess of crud from a probably 1” square. Thank you.
Thank you,
I’m saving and printing this information.
Originally Posted by GCG
Pressures vary not only with temperature, but with humidity and the RPMs of the engine, and without the last 2 parameters it's impossible to tell if your readings are normal or not.
A ∆T=30°F doesn't seem bad, but I suggest you retake your readings following the procedure summarized below and report back.
Take a look at this Post. It has detailed instructions to check/add refrigerant.
-These are the CliffsNotes:
First you'll need to find the current ambient temperature and humidity. Then, using the chart below, determine your target values for:
High Pressure
Low Pressure and
Center Vent Temp.
Now proceed to take your readings. Make sure you take them with (otherwise readings will be affected):
Are you certain you do not have air in the system? You have a variable displacement compressor which will adjust its displacement to hold to a fairly constant suction pressure. 35psi sounds a few psi too high and 250psi at 80deg ambient would be high if that’s what you were measuring while driving at 30mph. Sitting in your driveway, with the hood up and condenser fans running, that might be normal. I don’t know if C5’s cycle the condenser fans at idle or if they have continuous running fans at idle. There was a time when GM designed some systems to run the fans continuously at idle for noise and vibration reasons. The compressor control valve is actually biased to control to a lower pressure as discharge pressure increases so at 250psi it should be controlling to something below 30psi and the suction line would feel quite cold. At 35psi the suction line would be closer to 40 degrees. As you rev the engine, does the low side pressure drop to about 30psi?
Air in a system will raise discharge pressure but the compressor should still try to control to about 30psi. Blocked condenser air side as others have suggested will raise discharge pressure. I assume your condenser fans are running??
Not knowing anything about the history of your car, here are some guesses: 1. Air in the system. 2. Bad compressor control valve 3. if your suction line is cold, there may be something wrong with the air side. The evaporator normally lowers the air temperature as close to 32 degrees as possible without freezing. The cold air is then blended with air from the heater to keep the cabin at your temperature setting. 4. If the suction line is warm, low refrigerant charge.
Looks like tomorrow I’m hitting Horrible Freight for a long nozzle blow gun. I removed the cover, hit it with compressed air and blew out a mess of crud from a probably 1” square. Thank you.
LOL - I also used the hose to get a lot out. Some of that stuff is really stuck in there.
Thanks for the tips and education everyone! I just used Ed’s advice on blowing out the condenser seemed to do the trick, at least at idle, I haven’t yet taken it out on the road this morning, I’ve got no coffee down my neck yet, it’s 75 degrees out and after Ed’s tip, blowing 32ish degrees (Analog thermometer and poor cyclops vision) at the vent. Pressures are 30 low Side, up to 225 High side. Thanks again everyone, now to get some coffee, finish oil change on the mower then cut grass.
Thanks for the tips and education everyone! I just used Ed’s advice on blowing out the condenser seemed to do the trick, at least at idle, I haven’t yet taken it out on the road this morning, I’ve got no coffee down my neck yet, it’s 75 degrees out and after Ed’s tip, blowing 32ish degrees (Analog thermometer and poor cyclops vision) at the vent. Pressures are 30 low Side, up to 225 High side. Thanks again everyone, now to get some coffee, finish oil change on the mower then cut grass.
WHAT your suppose change oil on mower?? I guess after 15 years maybe i should change it. I thought it was like an air compressor,. 30 years and still running strong. U know what i'll put off for awhile i have a lot of motorcycle riding to check up on. Hope there is even oil in it. Craftsman run forever.
WHAT your suppose change oil on mower?? I guess after 15 years maybe i should change it. I thought it was like an air compressor,. 30 years and still running strong. U know what i'll put off for awhile i have a lot of motorcycle riding to check up on. Hope there is even oil in it. Craftsman run forever.
I think you’re supposed to, I never have on my push mowers, they’re reject motors from Evinrude if memory serves correct. My ZeroTurn operated much better today since changing hydrostatic oil and filter.
99 C5 AC aggravation
