North American Turbocoupe Organization



AC compressor cycling
MN88TurboCoupe Offline
Member
#1
I've read a little bit on some other threads.

I charged up my system and it shows about 50lbs.  I did convert to R134a and changed out the various o-rings. 

It will only cool when I have it at 60 degrees and the compressor cycles on about every 3 or 4 seconds.

Ideas or what can I do to test?  I don't mind it at 60 since I just change fan speeds so it doesn't get to chilly
Publicity, fame and accolades can make a theory popular. They can't make it true.
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anasazi4st Offline
Senior Member
#2
(06-28-2019, 01:51 AM)MN88TurboCoupe Wrote: I've read a little bit on some other threads.

I charged up my system and it shows about 50lbs.  I did convert to R134a and changed out the various o-rings. 

It will only cool when I have it at 60 degrees and the compressor cycles on about every 3 or 4 seconds.

Ideas or what can I do to test?  I don't mind it at 60 since I just change fan speeds so it doesn't get to chilly

Did you flush out the system (except the HR-980 compressor) with recommended a/c flush? Did you vacuum out the system for an hour or two and wait a bit to see if it holds that vacuum? Did you also change out the receiver/dryer (or accumulator if you prefer) and the orifice tube—all of which is recommended in the Tech Article found on here about r-134a conversion?

Do you have a set of a/c gauges? While not absolutely necessary, *I* wouldn’t mess with the system without them. Harbor Freight has an acceptable set for around $60.

I converted mine in January 2016; since then even though we have 115+ degree heat here in the summers it has always provided plenty of very cool air when needed. I followed the instructions in that article (with a few minor modifications). I read lots of gloom and doom stories about how it wouldn’t be as good as R-12 or that I would not be happy, so I put it off for 10 years. SPOILER ALERT: I could not be happier with the results, and in my case I think it’s as good as R-12 (but I also did other things like carefully cleaning then combing out the radiator and evaporator fins, for example).

If you didn’t do all of the things in that article you probably aren’t going to have very good results.

If your compressor is cycling every 3-4 seconds then it’s either a) not very hot outside or b) you don’t have enough Freon; or there’s something else wrong, like water vapor in the system, which you shouldn’t have if you did all the things I mentioned.

My experience is that even at around 80 degrees there should not be much cycling.
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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Jeff K Offline
Administrator
#3
^^^^^ Agree 100% with everything you said.

When switching any R12 system to 134a, you only use about 80% of the R12 system capacity worth of 134a.

Another remote possibility is the CCPS (switch sticking out from the top of the accumulator/dryer) isnt switching on/off at the correct pressures.

I assume the old oil was flushed out and replaced with the correct amount of PAG46 134a compatible oil and the accumulator/dryer was replaced?

Did you replace the orifice tube?

What are the higi and low side pressures when the compressor turns on? off?
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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MN88TurboCoupe Offline
Member
#4
(06-28-2019, 08:09 AM)anasazi4st Wrote:
(06-28-2019, 01:51 AM)MN88TurboCoupe Wrote: I've read a little bit on some other threads.

I charged up my system and it shows about 50lbs.  I did convert to R134a and changed out the various o-rings. 

It will only cool when I have it at 60 degrees and the compressor cycles on about every 3 or 4 seconds.

Ideas or what can I do to test?  I don't mind it at 60 since I just change fan speeds so it doesn't get to chilly

Did you flush out the system (except the HR-980 compressor) with recommended a/c flush? Did you vacuum out the system for an hour or two and wait a bit to see if it holds that vacuum? Did you also change out the receiver/dryer (or accumulator if you prefer) and the orifice tube—all of which is recommended in the Tech Article found on here about r-134a conversion?

Do you have a set of a/c gauges? While not absolutely necessary, *I* wouldn’t mess with the system without them. Harbor Freight has an acceptable set for around $60.

I converted mine in January 2016; since then even though we have 115+ degree heat here in the summers it has always provided plenty of very cool air when needed. I followed the instructions in that article (with a few minor modifications). I read lots of gloom and doom stories about how it wouldn’t be as good as R-12 or that I would not be happy, so I put it off for 10 years. SPOILER ALERT: I could not be happier with the results, and in my case I think it’s as good as R-12 (but I also did other things like carefully cleaning then combing out the radiator and evaporator fins, for example).

If you didn’t do all of the things in that article you probably aren’t going to have very good results.

If your compressor is cycling every 3-4 seconds then it’s either a) not very hot outside or b) you don’t have enough Freon; or there’s something else wrong, like water vapor in the system, which you shouldn’t have if you did all the things I mentioned.

My experience is that even at around 80 degrees there should not be much cycling.

I vacuumed out my system since I already replaced/converted the other components to r134a I added oil (1 oz oil, 1 oz r134a and 1 oz conditioner) plus 2 12 oz cans of r134a.  

It's no longer cycling like it was but now when I have it set to any temperature other than 60 it blows hot air.
Publicity, fame and accolades can make a theory popular. They can't make it true.
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Jeff K Offline
Administrator
#5
If only cold air at 60 F setting, the issue is with the EATC system, not with the AC system itself. Either electrical issues with the blend doors, mode doors, various EATC temp sensors, etc. Modern Ford EATC systems are easy to troubleshoot but the TC EATC system is no where near as easy. There are a series of button presses on the EATC head that will run some primitive tests, but I have no clue what they are.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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anasazi4st Offline
Senior Member
#6
The easiest method would be to obtain another EATC control head unit—the thing that sits in the dash with the buttons that operate it. Swapping it out is easily done; if that one also fails to perform properly there is a more serious issue present.

The self-test diagnosis Jeff mentions is available by pressing the OFF/AUTO and DEFROST buttons simultaneously, and then the A/C button within 2 seconds (this is according to the Ford shop manual, Volume B Part 1, page 36-75-46).

Error codes are displayed on the front of the control unit. It displays error codes found during the test as well as any found during normal operation.

To cancel the test, press the COOL button.

Here are the steps to prepare for the Self-Test, as listed:

1) Turn ignition off, then on, to reset the system.
2) Ensure engine is warm (at least 120 degrees coolant temp.).
3) Set control head to AUTO: 90 degrees.
a) Wait 40 seconds, minimum.
b) Verify that the system goes to high blower and that warm air is being discharged from the floor.
c) Verify that the the recirculating door is in the OUTSIDE AIR position.
d) Verify that warm air is bleeding out of the defroster nozzle.
e) Enter SELF-TEST.
f) Record all faults and error codes displayed.
g) Exit SELF-TEST.

Then, follow all the above steps but this time set the EATC to AUTO/60 degrees, wait minimum 40 seconds, ensure cool air is being discharged from the panel vents, enter SELF-TEST and record codes, exit SELF-TEST.

There are 18 pages in the manual listing the error codes and what they mean, as well as how to correct them.

I have performed this SELF-TEST several times over the years; it can be a big help in diagnosing EATC problems.
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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