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A/C unit is blowing warm air

Tiny
ASEMASTER6371
  • MECHANIC
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You should have one pin with battery voltage all the time. It should be 12.4 to 12.6. Looks like your battery is very low.

You have a terminal that has battery voltage with key in the start position only as well.

Check and confirm.

Roy
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Saturday, August 8th, 2020 AT 1:38 PM
Tiny
BWILKINSON05
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Roy,
I charged the battery (Interstate May 2019) overnight and it doesn't appear to be holding the charge. I will replace if necessary.
With key off (1 - top left, 2 - top right, 3, bottom right, 4, bottom left
1. 0v
2. 7.5v
3. 0v
4. 0v
with key on
1. 0v
2. 7.5v
3. 0v
4. 0v
Pin #2 is always live pin you mention above.
Please advise.
Bret
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Saturday, August 8th, 2020 AT 1:54 PM
Tiny
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Please test for voltage with the key in the start position and tell me one of the terminals has battery voltage.

You are missing the constant battery voltage reading as well. Check the ignition A 40 amp fuse for power. That is what supplies power. I attached the diagram of the fuse block back a few posts.

Roy
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Saturday, August 8th, 2020 AT 2:11 PM
Tiny
BWILKINSON05
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Roy,

Pin #2 (top right) is always on and reading 7.5v. The ignition A 40 amp fuse top flat pin closest to motor = 6.5-7v and bottom flat pin = 0v with key in start position.
I am currently charging battery and should get higher readings soon. Seems like I have an open circuit and battery is being drained.
Bret
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Saturday, August 8th, 2020 AT 2:27 PM
Tiny
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Charge the battery until it reads 12.6 volts.

Then test the fuse for voltage on both sides while installed. Then go to the relay and test for voltage.

Roy
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Saturday, August 8th, 2020 AT 2:32 PM
Tiny
BWILKINSON05
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Roy,
Here are my test results:
Battery = 13.17v
Fuse = 12.97 on each side
Relay:
(1 - top left 2 - top right 3. Bottom right 4. Bottom left)

with key in off position:
1. 0v
2.12.9v
3. 0v
4. 0v

with key in start position:
1. 0v
2. 12.34v
3. 4-12.25v (fluctuation probably due to not getting a good ground, once I did it held at 12.25v)
4. 0v

Thank you,
Bret
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Saturday, August 8th, 2020 AT 6:39 PM
Tiny
ASEMASTER6371
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Okay, when you hold the key to the start position, does the relay energize?

You have the proper signals to the relay at this point.

Roy
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Sunday, August 9th, 2020 AT 4:25 AM
Tiny
BWILKINSON05
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Roy,

When we tried to start vehicle, I felt a click in the starter relay. Should I disconnect the negative terminal for 10 minutes to clear the ECM and reprogram the passkey with the battery charger connected?
Bret
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Sunday, August 9th, 2020 AT 6:58 AM
Tiny
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No, disconnecting the cable does nothing. All that does is make the ECM forget codes. It programs nothing.

If the relay is clicking, go to the starter and see if there is power on the small wire at the solenoid in the start position. It should be a purple wire that is smaller than the battery cable.

Roy
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Sunday, August 9th, 2020 AT 7:03 AM
Tiny
BWILKINSON05
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Roy,
I would like to clarify, my truck starts but does not continue to run. I just checked and the battery and starter cranked fine. My assessment is the motor is not receiving fuel and not able to run. Is there another relearn process I need to complete?
Bret
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Sunday, August 9th, 2020 AT 10:33 AM
Tiny
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Okay, I attached the response below from you. You never said the starter worked at all.

Good afternoon! I installed the ECM and followed the Passkey III - transponder ignition key set up process (10 minutes with key on, 5 seconds with key off - 3x) and my truck will not start. Do you have any recommendations?

Since we are beyond the original issue, you need to start a new question from the beginning based on the new failure.

Thanks

Roy
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Sunday, August 9th, 2020 AT 10:37 AM
Tiny
BWILKINSON05
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Roy,

I apologize I got us on a tangent. I went through the ECM pass-lock reset process and it worked, my truck started. However, the compressor did not engage. Do you have a recommendation?
Bret
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Sunday, August 9th, 2020 AT 11:56 AM
Tiny
ASEMASTER6371
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Okay, no worries.

You need to go to the relay for the clutch, which I posted way back, and let us start with powers.

Did you check Freon pressures both high and low side?

Roy
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Sunday, August 9th, 2020 AT 12:03 PM
Tiny
BWILKINSON05
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Roy,

We tested the following:

low side sensor - 5v and 0V
high side sensor - first test we had 5v at one pin, 0v at two pins.
Jumped low side sensor - compressor clutch turned on.
Plugged low side sensor back in then removed.
With low side sensor jumped, tested high side sensor - 0v at all three pins.
Jumped A/C relay, ran A/C system confirmed Freon at a good level.
Jumped low side sensor, A/C clutch would not come back on and was surprised this was the case. I believe the test result initially indicated the low side sensor is bad but can't explain why we don't have 5v at two pins at the high side sensor and why the low side sensor jump won't turn the clutch back on.
Please advise.
Thank you,
Bret
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Sunday, August 9th, 2020 AT 1:04 PM
Tiny
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What is the high and low side pressure when you jumped the low pressure sensor?

Roy
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Sunday, August 9th, 2020 AT 1:14 PM
Tiny
BWILKINSON05
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Roy,
We were surprised the clutch kicked on and then could not get it to repeat which is why I jumped the relay to check the Freon level, blue and red are both at 110 psi.
Bret
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Sunday, August 9th, 2020 AT 1:23 PM
Tiny
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Okay, the low pressure switch voltage comes from the HVAC module as in the diagram.

The pressure transducer comes from the ECM. That should have 2 5 volt signals and 1 return.
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Sunday, August 9th, 2020 AT 1:29 PM
Tiny
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Was that the pressure while the compressor was running?

Roy
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Sunday, August 9th, 2020 AT 1:41 PM
Tiny
BWILKINSON05
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  • 68 POSTS
Roy,

Sorry for the delay getting back to you, we had to step out for a family event.
I ran the truck and re-read the gauges, blue = 30 psi and red = 150 psi.
I will remeasure the low side and high side pins tomorrow evening, I tested them multiple times and was surprised by the readings.
Bret
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Sunday, August 9th, 2020 AT 6:07 PM
Tiny
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Okay, keep me updated.

Roy
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Monday, August 10th, 2020 AT 3:36 AM

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