Hi All -

Earlier this summer I removed my entire AC system, including evaporator, condenser, compressor, accumulator hoses, etc. I generally followed all the great advise here on Thirdgen.org but in particular followed the steps and procedures per this post by Liquid Blue https://www.thirdgen.org/forums/cool...sion-here.html Thanks Jim!

Upon flushing out the system I reinstalled everything including a new compressor, accumulator, adjustable orifice tube and Schrader valves. Added PAG oil and refrigerant, reconnected the switches and sensors and started it up. Everything seemed to be working well. My operating low pressure readings were between 20 to 45 PSI while the high pressure was in the 150 - 250 PSI range. The center vent temperature was generally in the 52 to 54 degree range. A few times dipped into the upper 40's.

The one thing I noticed from day one was how hot the compressor gets. Is this normal?? It's been a number of years since my AC was properly working and I don't recall ever really checking or noticing if the compressor was hot. Recently, my AC temp in the car has been noticeably warmer, generally 58 - 60 degrees. Along with the hot compressor is a hot discharge line. I connected the gauges last night and ran the car for quite a while. Pressure readings still seem normal. Clutch is engaging and disengaging normally, but vent temp still warmer than it should be. This morning the static pressure on both gauges was 80 PSI at 74 degrees in the garage and about 80% relative humidity outside.

I would appreciate any help or insight anyone can offer or other suggestions of something to check on.

Thanks!
Pete

 

Pressure looks pretty good, do you have a heater control valve to shut off the hot water from flowing through the core?

 

That's how a refrigeration system works... The compressor squeezes the gas raising it's pressure and temperature so it's above ambient. That hot gas then goes to the condenser where it gives up heat to the air passing thru... Most HVAC systems use hot gas at 125 f or above to ensure proper heat transfer... So the discharge line should be pretty hot... If it's not, the system will not cool...

 

I do have the bypass valve that located behind the compressor that is to shot that off when AC is on. All the vacuum hoses are connected and appear to be running properly.

 

Thanks for the info. I didn't realize it ran that hot. I did a check and I was getting a heading on the outside of the compressor and discharge hose in the 130+ temperature range. Maybe I just need to do some more fine tuning.

 

In 102°F mine was almost 170°F and that is well under Sandens limit.

 

Try testing your a/c after the car has been sitting all day in the shade / garage, where ever. or first thing in the morning, before it gets hot outside. test it at start up before engine warms up and see what your vent temp are. the sun and engine heat things up and it takes a good while before the a/c can cool down all the plastic inside the vents, etc. the heat stored in the vent plastic ends up blending with the cool air the a/c puts out.

this will give you and idea of what it is doing under best conditions. if your vents are still running hot during this test, then it could be a a/c problem. if the vent temp is cooler, then maybe you have an air leak somewhere, allowing outside hot air to blend. which, heater door is a big suspect. did you ever verify if the heater door actually closes completely?

 

I did as you suggested. The temperature at the center vent upon start-up yielded temps between 50 and 52 degrees, so I think the AC is probably working as it should. I've seen mention in a few threads to sealing the heater door as well as the door that let's in fresh air. Are these areas easily accessible?

 

50 - 52 sounds too warm to me. you're fresh air door wont have as much impact when the engine if first started up, the engine is not hot yet. the fresh air door is down by the passenger feet, sort of in the middle of the car. I accessed mine when the evaporator was out for flushing. if your vents tubes are all intact, then 50-52 seems too warm, maybe others can say what they get.. seems like you should be able to get down to 40 with little issue, I I was getting 35.9 in the garage, in shade on a July day, so it was hot outside.

How many cans of r134a did you put into the system? The system is designed to take X-pounds, and it says what that is somewhere. that may also be in the thread. Added about 2.5 to 2.75 12 oz cans of r134a

What kind of orfice did you use?

Have you checked your pressure switch, I think some of them are adjustable.

 

Thanks for the comments, JIm. I was amazed you were able to get down to 35 degrees. According to the table you posted, shown below, for outside temp of 70 degrees at 60% humidity the center duct temp should be about 53 degrees. I would like the center vent temperature colder but based on this I figured this was about what I could/should expect.


I put in approximately 2.75 cans of R134a. I used the same adjustable orifice that you used and referenced. I also did adjust the pressure switch on the accumulator. All of the pressure switches are original. They all seem to be working. Did you replace all of yours?

If anyone has any additional comments/suggestions I'm all ears.

 

That table looks as bogus as a $3 bill to me.

My guess is, it's the factory's "Get out of my face you stupid customer" excuse when somebody brings in a car that doesn't cool. Kinda like the "LS1s are OK to use a quart every 1000 miles, see says it right here in this TSB".

Weasels.

 

LOL on the table. I have heard by at least one person not to mess with the variable orifices, but I've had good luck with it. Instructions say it improves cooling at idle.

BTW - what is your air vent as you are going down the road, same conditions but car warmed up? If its about the same, you're vent door may be fine. you may be able to pull on the warm/cool air blend and listen to the door open and close if you can get all the kids out of the garage.

And one other thing, think I always run MAX A/C. if there is such a thing, haven't been over to the car in a while.

what type of oil did you end up using?

 

Once the engine is warmed up the center vent temperature increases to about 57 - 59 degrees (on max AC).

I used PAG oil (AC Delco 15-188) from Amazon as recommended for the new AC Delco compressor instructions.
I have the bypass valve so if "heat" is not selected coolant shouldn't be running to the heater core, correct? But if the door is not properly sealed I assume heat from the engine compartment itself can get in. Same with the fresh air door too?

 

yes, hot water can slip by into the heater core if valve doesnt shut completely. same with hot air on fresh air vent. both would make cabin temp rise. Another point of failure is the front end of your car. All of the air dams, air flow plastic underneath need to direct air up to condenser. and make sure condenser has insulation on the sides so air goes thru the condenser, not around it. want to keep that condenser cool and fresh air flowing across its fins.

 

Thanks Jim. I thought the oil was PAG 150. As for the conversion, I removed all the components from the car and completely flushed with mineral spirits. Shouldn't have been any oil left in the lines and other remaining components. The compressor is new. I removed the condenser as well, cleaned the fins and re-installed. The insulation all seemed to be in good shape as are the air dam components. Right now I'm thinking the vent doors maybe aren't closing completely.

Thanks for the insight.

 

I'm heading over to the Formula today, if I have time, will fire it up and see what vent temp readings I'm getting. get a sanity check. Its been a few years now. keep in mind, I'm not using some lab certified, calibrated thermometer, but good enough for these purposes.

I've read you can't get all the residual mineral oil off the rubber lines, nor do you want to, provides protection for the rubber. I would also think its hard to completely flush all oil out of the system, some is just gonna stick. that is why I went with ester. makes me wonder if maybe your orifice is sticking or something. who knows, but I'm running out of ideas, but it sure seems like you should be able to do better than 52 at startup. I'm 1200 miles south of you, much hotter here - especially in July.

 

just did the sanity check, test results over here, https://www.thirdgen.org/forums/cool...ml#post6478754

I may come back and edit when I have time.