A/C experts please.
Thread Starter
Burning Brakes
Joined: Apr 1999
Posts: 797
Likes: 1
From: EUNICE, La
A/C experts please.
Here is the story. Origional POA set up on the 69, along with the expansion valve were sticking. I would freeze up after about 15 mins of highway speed.
Cleaned everything up while doing my 383 build up. Now I have an R4 surpentine set up. Gone is the large A6. I also went with Old Air products POA eliminator kit. Using R12 because down here in south La It's always very hot and humid!!!
Not getting very good performance from the ckutch cycling eliminator kit. To long between cycles. When the low side gets to 27 lbs the low pressure switch shuts down the compressor, but the equalize time for the compressor to start up again is too long and the evap gets warm, that means warm air out the vents. Then the comp starts up and cold air comes out.. this sucks.
Now for the question, can a brand new R4 run continues like an A6 if I go back to a new POA valve and new expansion valve with R12.
Thanks Thad
Cleaned everything up while doing my 383 build up. Now I have an R4 surpentine set up. Gone is the large A6. I also went with Old Air products POA eliminator kit. Using R12 because down here in south La It's always very hot and humid!!!
Not getting very good performance from the ckutch cycling eliminator kit. To long between cycles. When the low side gets to 27 lbs the low pressure switch shuts down the compressor, but the equalize time for the compressor to start up again is too long and the evap gets warm, that means warm air out the vents. Then the comp starts up and cold air comes out.. this sucks.
Now for the question, can a brand new R4 run continues like an A6 if I go back to a new POA valve and new expansion valve with R12.
Thanks Thad
Racer
Joined: Dec 2002
Posts: 421
Likes: 2
From: Long Grove, IL
There is no reason I am aware of that would prevent an R4 compressor from running continuously like the A6. That said, the pressure switch that cycles the compressor on and off is adjustable. If you remove the connector to the pressure switch you should see a small screw in the middle of the two connectors. It has been a while since I fooled with a GM CCOT (Cycling Clutch Orifice Tube) system but just turn the screw one way and see if the low pressure goes up or down before the compressor cycles off. What you want is a lower low pressure before the compressor cycles off. The delta between the compressor on and off is not adjustable so all you can do is move the entire range lower - does this make sense?
Example:
Current - compressor off at 27# and on at 50# - delta = 23
New - compressor off at 20# and on at 43# - delta = 23
By moving the range lower you will keep the evaporator from getting too warm before the system engages again however there will always be a noticeable change in vent temperature in a CCOT system as the compressor cycles on and off.
Hope this helps.
Jay
Example:
Current - compressor off at 27# and on at 50# - delta = 23
New - compressor off at 20# and on at 43# - delta = 23
By moving the range lower you will keep the evaporator from getting too warm before the system engages again however there will always be a noticeable change in vent temperature in a CCOT system as the compressor cycles on and off.
Hope this helps.
Jay
Racer
Joined: Dec 2002
Posts: 421
Likes: 2
From: Long Grove, IL
Originally Posted by comp
does that low of pressure cut off cause(help) the freeze up ????
Also, the pressures I listed were only an example. You also have to be aware of the high side pressures in the system and make sure that they do not go too high. How high they go will depend upon outside air temp, air flow over the condenser and how long the compressor runs before cycling off.
Setting up a cycling clutch system is a lot like tuning a carb; you should make small changes and validate the results rather than making one radical change.
Jay
Last edited by griffths; Jul 30, 2004 at 10:25 PM.
Racer
Joined: Dec 2002
Posts: 421
Likes: 2
From: Long Grove, IL
Originally Posted by comp
OK and doesn't r-12 have about the same temp as low pressure ???
so if it goes to 24deg.(or 24psi) it will be freezing the evap.????
so if it goes to 24deg.(or 24psi) it will be freezing the evap.????
Jay
Last edited by griffths; Jul 30, 2004 at 11:07 PM.
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Can you supply the PSI readings for both the high side and low side? This will help us to help you. How often does the clutch cycle, at what rpm are you running the engine to check the system, how much refrigerant (oz) did you charge the system with?
Neal
Neal
