A/C unit is blowing warm air

Tiny
BWILKINSON05
  • MEMBER
Roy,

Tonight I tested the following after letting truck run for a few minutes to allow A/C pressure to stabilize (see attached picture), Freon seems a little low:

Low Side:
0v and 5v
jumped the low side connector, the compressor did not come on.

High side connector:
red = 0v
white=5v
black =0v

I also re-read the air conditioning not working article and am wondering if I have enough power at the low side sensor, the article indicates I need for 12v.

Where should I test next?
Should I add Freon to confirm the low side jump, I read the system needs to be at 25 psi for the test to work properly.

Thank you,
Bret
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Monday, August 10th, 2020 AT 5:12 PM
Tiny
BWILKINSON05
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Roy,

I studied the schematic's further. How likely is it the climate control module is not sending the proper signals to the low side sensor and ECM? Should this be our next test?
Bret
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Tuesday, August 11th, 2020 AT 4:15 AM
Tiny
ASEMASTER6371
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No, the fact the system is working eliminates the sensors and the wiring.

I cannot read the pressure you posted. The picture is too small and cannot make out the readings. Can you either take a picture I can read or just tell me the high and low side pressures?

Roy
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+1
Tuesday, August 11th, 2020 AT 4:21 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,
10-4. Blue gauge = 25 psi, red gauge = 110 psi.
Thanks,
Bret
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Tuesday, August 11th, 2020 AT 6:02 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, how much Freon did you add?

What is the outside temperature?

The low side is perfect.

The high side is low. It should be 2 times ambient plus 15%.

Roy
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Tuesday, August 11th, 2020 AT 6:04 AM
Tiny
BWILKINSON05
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Roy,

Since I started this project I have added two Carquest 12oz cans and 1-20oz A/C ProUltra Synthetic can of 134a. Outside temperature is 85-95 degrees, we are in Richmond, Virginia.
Bret
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Tuesday, August 11th, 2020 AT 6:26 AM
Tiny
ASEMASTER6371
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The high side should be around 200-205.

With 34 ounces, it should be overcharged.

Do not add that synthetic stuff. Not needed and does nothing.

Just use the standard 134.

Did you add 34 ounces in the system at this time?

Roy
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Tuesday, August 11th, 2020 AT 6:34 AM
Tiny
BWILKINSON05
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Roy,

10-4 on the synthetic. I added 1/2 the synthetic first several weeks ago before I bought the gauges you recommended. When the gauges arrived, I vacuumed the system down and added 1-12 oz can until I reached about 50 psi and then have added more, as necessary.
Bret
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Tuesday, August 11th, 2020 AT 7:21 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, that is better.

You should have added 1.6 pounds. Do not pay attention to the gauge on the cans. That is not what you go by.

How much do you have in the system at this time?

Roy
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Tuesday, August 11th, 2020 AT 7:26 AM
Tiny
BWILKINSON05
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Roy,
The last time I added Freon I estimated I was in the 1.5 pound range and I recall you thought the PSI readings were in good shape. The blue is lower now then previously. My July 18th pressure readings were blue = 43 psi, red = 240 psi.
Bret
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Tuesday, August 11th, 2020 AT 7:37 AM
Tiny
ASEMASTER6371
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Correct.

Are you still having issues? Is the air not cold?

Roy
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Tuesday, August 11th, 2020 AT 7:45 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,
The air is cold if I jump the relay but the compressor will not turn on unless its jumped. From what I can tell the compressor and overall system is fine just not getting the signal to turn on the compressor.
Bret
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Tuesday, August 11th, 2020 AT 7:57 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, we will go over this again.

30 and 87 are good for the relay as the compressor comes on when you jump it.

86 has to have power as well.

85 is grounded by the ECM once it sees the correct signal from the low pressure switch and the pressure sensor.

Do you have power at the low pressure switch?

Do you have 2 5 volt powers at the pressure sensor?

Roy
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Tuesday, August 11th, 2020 AT 8:03 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,

I have 5v at the pressure switch and 1-5v line (white line) at the high pressure switch. I believe I need 12v at the low pressure switch and believe that may be the issue.
Bret
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Tuesday, August 11th, 2020 AT 8:06 AM
Tiny
ASEMASTER6371
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At the pressure switch, you need 2 5 volt pins. Do you have that?
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Tuesday, August 11th, 2020 AT 8:21 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,
At the high side, I do not. We expected the ECM to correct this but the results are the same.
Bret
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Tuesday, August 11th, 2020 AT 8:36 AM
Tiny
ASEMASTER6371
  • EXPERT
I know I also stated the wiring to the ECM could be the issue. Did you verify the wire was good to the ECM on the wire that did not have voltage?

Roy
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Tuesday, August 11th, 2020 AT 8:41 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,

Do you want me to test the new ECM at pin #14 (ECM to battery ground) and from the high side red line to the ECM (pin to pin)?
Bret
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Tuesday, August 11th, 2020 AT 8:44 AM
Tiny
ASEMASTER6371
  • EXPERT
At pin 14 on the new ECM, back probe it and test for voltage.

Roy
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Tuesday, August 11th, 2020 AT 8:47 AM
Tiny
BWILKINSON05
  • MEMBER
Roy,

I tested the following with key in the on position:

1. Back probe with paper clip at pin 14 with harness plugged in 0v.
2. Removed harness, paper clip front of harness, 0v.
3. Pin to Pin - pin 14 to high side sensor red pin - 0 ohms, continuity should be good.

What do you recommend I test next?

Thank you,

Bret
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Tuesday, August 11th, 2020 AT 3:40 PM

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