A/C unit is blowing warm air

Okay, I sent another diagram for you. The 2 wires I circled need 5 volts. Tell me which one does not have power. That power comes from the ECM. You may have a bad ECM or the wiring to it.

Could you please tell me those readings as I cannot see them. It is way too small to see.

Roy

Roy,
I measured the three pins at the high side connector:
middle/top pin = 0V
left pin = 0V
right pin = 0-5V (this one wasn't consistent and would hold at 0V and then drift up to 5V)
I will measure again tomorrow.
Bret

That is the issue. You need the correct amount of voltage at the wire for the system to work correctly.

Roy

Roy,
I remeasured the readings at the high pressure switch and show the following:

w/paperclip:
Top = Red = 0V
Left = Black = 0V
Right = Grey = 5V after it set

w/o paperclip with relay installed:
Top = Red = 0V
Left = Black = 0V
Right = Grey = 0V

I reviewed the schematic drawing you sent last Saturday at 11:29 AM, I believe the pressure sensor is the bottom right above the ECM. The grey shows 5V, the other two do not indicate a voltage. Does the red also need 5V? Where do you suggest I start with my testing?

Bret

Yes, the red wire is missing the signal.

I attached the pin you need to test at the ECM for power to help determine whether it is a wring issue or the ECM.

I attached the connector as well. Check pin 14. Back probe it for 5 volts.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

Roy,

I have removed the ECM rows/strips. Is mine on the green or blue strip? I found red wires with black stripes on both.
Bret

At pin 14. there should only be one red wire. the other connector does not have a red wire at pin 14.

Roy

Roy,

I tested the green strip in all 4 locations i.e. 14 slots from the left, top and bottom and 14 slots from the right, top and bottom with paper clips with the key off and in the on position. All 8 tests = 0 ohms per the instructions. I used a paper clip in the ECM and paper clip in the high pressure sensor red line. Is this correct? Should I instead test for volts connecting a probe to the paper clip at the ECM and the other to ground?
Bret

With everything hooked up with the key on, put the paperclip at the back of pin number 14 with the red wire and test for 5 volts. Red lead on the paper clip and black lead to a good ground.

Roy

Roy,
I tested the #14 pin on the green strip top and bottom from each end - 0V for each test, total of 4 tests. This was the only strip with a red line near the 14 pin.
Bret

Okay, without that output, the A/C will not work.

Looks like you need an ECM.

Roy

Roy,
10-4. Is a signal sent from the climate control module to the relay we can test? If there is and the signal is not being sent, would that explain why the relay isn't turning on the clutch.
Bret

It is because the ECM is bad.

Replace it and let us see if it fixes the issue.

Roy

Roy,

I studied all our correspondence, now follow the schematic much better and also realized I did not back probe pin #14 properly. The first time I probed pin #14 from the green side not the back of the harness which I tested tonight with the harness connected to computer. I confirmed 0V - 1.2V still not enough and proving the ECM is bad. Where do you recommend I buy the ECM? I found one at Flagship1 for $150.00 with a lifetime warranty.
Thank you for your input.
Bret

You could go with that. Make sure it is programmed to your VIN number to work.

Roy

Roy,

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?
Bret

Is the theft or security light on after 10 second with the key on?

Roy

Roy,

The security light came on during the first 10 minute cycle and turned off after approximately 7 minutes. It did not come back on during the 2nd and 3rd 10 minute cycles.
Bret

Okay, it is not a security issue.

I attached a diagram for you of the starting system. You need to see if the ECM is grounding the control side of the relay at the pin I circled.

Roy

Roy,
We tested the starter relay in the fuse box with key on and off:
1. Bottom left pin (front of vehicle) with the back top right pin ranged = 9-11.5V
2. Top left pin (front of vehicle) with the back bottom right pin = 0v
3. Left top and bottom pin = 0v
4. Right top and bottom pin - range from 7-11.7v
Bret

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

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

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

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

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

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

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

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

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

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

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

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

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

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

What is the high and low side pressure when you jumped the low pressure sensor?

Roy

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

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.

Was that the pressure while the compressor was running?

Roy

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

Okay, keep me updated.

Roy