A/C unit is blowing warm air

Roy,

We retested the battery, pressure sensor and relay with a different multi-meter:

Battery = 12.4V
Pressure sensor = 4.8V
Relay = 13.8-14V

I reviewed the "air conditioning not working" summary on your website and the pressure sensor test results indicate the climate control computer is bad. Do you agree? What do you recommend at this point?

Best regards,
Bret

Roy,

We tested the pressure sensor near the fire wall which I believe is the low side pressure sensor. It has two ports and read 4.8V with the key on. Where is the 3 wire sensor?
Bret

Roy,

We double checked and confirmed the high side connector was two pins. When we jumped I notice a slight draw on the motor but the clutch did not turn on.
I test the three pin connector near the compressor, see attached picture and it read 5V. I also noticed but did not test a connector on the compressor.
Bret

Roy,

We jumped the low side pressure sensor connector in the attached picture, I noticed a slight draw on the motor but the clutch did not kick-on. There is a second connector near the low side sensor, see blue connector in picture but I do not see a place to plug in.

Bret

Roy,
I just tested the blue connector in the picture and it read 0V. I just noticed it this morning, not sure why it's there.
Which other sensor are you referring to?
Bret

Roy,
We tested the high side pressure connector which read 5V, see picture which I believe matches the location #4 and #5 in the #3 diagram you sent at 8:22 this morning.
Please advise.
Bret

Roy,
I have attached a close up of the wires on the high side connector. I see red, grey and white.
Bret

Roy,
Yes, we tested with two paper clips and it read 5V.
Bret

Roy,
For reference, on occasion (over 2-3+ years), the HVAC system would blow hot air when set to cold. The immediate fix was to turn off the vehicle and turn back on. Most of the time this reset the system. This issue could have been caused by the Climate Control Module but we thought it was the driver blend door because the driver side was the only side running hot, passenger was normal. This is why we removed the blend door when we started diagnosing the current problem. As you recall the HVAC unit without the blend door blew warm air on both sides with the blend door manually set to the cool position.

Also, the blower motor resister would burn out approximately every 1-2 years which would turn off the fan. Either the replacement blower motor resister was not a quality part (BWD from Advance) or I figured the unit was frying due to another component.

Based on our testing and the low side connector reading 5V versus 12V comparing to your websites "Air Conditioning not working" instructions, I thought this may indicate the Climate Control Module needs replacement or further testing:

"A pressure sensor is used to measure the amount of refrigerant is in the system. When this sensor goes bad the compressor will not turn on. To test this sensor remove the wiring connector and insert a jumper wire between the two terminals of the connector. If the compressor turns on the sensor is bad or the system is low or overcharged. If nothing happens use a test light to see if there is 12 volts at one of the wires. If no power is present suspect the climate control computer being bad."

Is there another test we can run to isolate the Climate Control Module to evaluate? All other tests seem indicate the system is running properly from an electrical perspective. Let me know what additional tests you recommend we run.
Thank you for your input.
Best regards,
Bret

Roy,

I tested the high side connector with 3 wires. I show 5V from one point and 0V from the other two.

Bret

Roy,

We ran another test to check the compressor. We jumped the relay with a paper clip and the compressor clicked. With the jumper in place the clutch also engaged while the vehicle was on.
Bret

Roy,

Here is the latest update:

1. I jumped the compressor relay with the paperclip
2. The Freon had run low so I added a new can 12 oz and the remainder of the A/C Pro can, approx 6-8 oz.
3. Allowed the system to run for awhile, please see charge levels which I believe are spot on per the gauge manual.
4. As a test, I removed the paperclip and the compressor clutch stopped, kept jumper clip installed.
5. The air in the cab was cool but not extremely cold at the lowest setting of 60 F
6. I believe this rules out the climate control module and indicates a switch is bad, I guess I would start with the low side.
7. Is it a fair estimate the relay is okay, if I switched with the horn relay and the horn works with both?

Thank you for your comments.

Bret