A/C unit is blowing warm air

Tiny
BWILKINSON05
  • MEMBER
  • 2003 CHEVROLET 1500
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
On my truck listed above Silverado 1/2 ton. I removed the blower resistor which cooled the air some and manually tested hot to cold. I believe the actuator was bad. I have tested the Freon level which appears normal. I have never added Freon since purchasing in 2003, is this a good starting point to add Freon if the gauge reads mid-range? I am going to follow your tests in the "How to fix your cars air conditioner in minutes!" video, what time do you close today?
Saturday, July 11th, 2020 AT 11:12 AM

130 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
We do not close. There is normally someone always here to assist but normal turn around time for questions will vary depending on your location.

Couple questions about your system. Do you have an automatic temperature control system or manual? Also, do you have dual temperature zone, meaning can you change the passenger side temp different then the driver side?

I suspect you are correct with the actuator but we just need to identify what system you have in order to confirm it. Thanks
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Saturday, July 11th, 2020 AT 11:19 AM
Tiny
ASEMASTER6371
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Good afternoon.

Do you have a set of gauges that can give me the high side and low side readings of the system? I need to see those readings in order to be sure the pressures are correct.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Is the compressor clutch engaging?

As far as the blend door, can you hear it move when you command cool to hot?

https://www.2carpros.com/articles/replace-blend-door-motor

I attached a wiring diagram in case the compressor is not working.

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

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Roy
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Saturday, July 11th, 2020 AT 11:29 AM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

Thank you for getting back to me. I do not have gauges and am considering buying one of these sets the Kozyvacu ($119.00) A/C repair set or the Xtremepower set ($129.00) or do you recommend a different set? I found the link to Amazon in one of your articles.

To provide some additional information, I initially thought the driver blend door wasn't working and removed from the vehicle. I manually switch from hot to cold setting and could tell a difference. Before removing the driver vents ran hot only and now I can switch from hot to cold which on the cold setting the air is warm.

After removing blend door, I watched the video and decided to add some R134a although my gauge that came with the R134a indicated mid to upper green range. I did this to test the compressor which cycled on then stopped. I felt the tubing at the high side tube and it felt cold but then warmed up when the compressor stopped running. Tomorrow evening I will test the relays and fuse to eliminate. Please advise on the A/C repair set and I will order. At this point, my best estimate is the compressor needs to be replaced.

I appreciate your time and input.

Best regards,
Bret
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Sunday, July 12th, 2020 AT 7:25 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The ones for 119 are fine.

Do not assume the compressor is bad at this point. That is an expensive guess as it may not be that at all.

https://www.2carpros.com/articles/replace-air-conditioner-compressor

If the compressor is coming on line when adding the freon, most likely not electrical. I attached the wiring diagram for the compressor circuit for you as well. It is in the first on my responses.

Let me know the results of the gauge readings.

Roy

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Monday, July 13th, 2020 AT 3:38 AM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

Good evening! I received my gauges this evening and completed the following:

1. Tested, 0 psi on both blue and red.
2. Vacuumed system for 30 minutes.
3. Let system rest for 30 mins, gauges held at -30.
4. Attached gauges and attempted to add Freon which would not take.
5. Started truck.
6. Removed blue adapter from low side, attached hose that came with the refill bottle, added Freon up to approximately 50 psi.
7. Low side line into firewall got cold.
8. Compressor did not cycle on.
9. Reattached blue adapter to low side.
10. Some Freon escaped, quickly closed valves.
11. Observed blue gauges decline to approximately 20-25 psi, estimate this occurred because the compressor did not turn on and pressurize system.
12. Red gauge held at approximately 20-25 psi.

Please advise as to the next step. Thank you for your time and advice.
Best regards,
Bret
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Thursday, July 16th, 2020 AT 7:43 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, the compressor did not kick in because the pressure is too low. 20 pounds on the low side and the low pressure switch will not close and turn on the compressor.

You need more Freon for the compressor to come on line.

I am concerned you had 0 pressure when you started. Did you check for a leak?

https://www.2carpros.com/articles/air-conditioner-leak-detection

Roy
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Thursday, July 16th, 2020 AT 7:51 PM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

That's what I thought regarding the compressor but the low side gauge read 60 psi after filling from the can which was more than the acceptable range provided. I was concerned about overcharging even though I have only used 11 oz from the can. Should I add the remaining 9 ounces and see if the compressor kicks on?

I read the check for leaks after vacuuming is confirming the gauge holds at -30 which the system did. How do I check for leaks?

This morning we tested the system again and attached a picture for your reference.

Best regards,
Bret
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Friday, July 17th, 2020 AT 7:59 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
The gauges are showing 0. The compressor will not come on until there is pressure.

The system holds 1.6 pounds.

Fluid Types

Refrigerant Type. R-134a

Important

Do not mix R-12 refrigerant and R-134a refrigerant, even in the smallest amounts. R12 and R-134a are incompatible with each other. If the refrigerants are mixed, compressor failure is likely to occur.
Capacities

Refrigerant Charge. 0.7 kg (1.6 lbs)

Refrigerant Charge with Front and Rear A/C. 1.13 kg (2.5 lb)

With the engine off and fully charged, the high and low side should read the same pressure. That pressure will be close to the ambient temperature of where you live.

Start by charging the system.

As far as a leak, I attached the guide for checking the leak with either a UV light or a bright LED light.

Roy
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Friday, July 17th, 2020 AT 8:07 AM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

Sorry I missed the leak link which I have now read. Assuming no Freon has leaked, so far I have added approximately.69 lbs. Should I finish the can (.55 lbs) or buy a second one and add until I reach 1.6 lbs? Do you recommend buying a leak detector (Elitech WJL-6000 on Amazon) before adding additional Freon?
Bret
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Friday, July 17th, 2020 AT 8:31 AM
Tiny
ASEMASTER6371
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I would continue the charge until full. Leak testing is done with a fully charged system.

Yes, the UV would be good to get. You can get them at most parts stores.

Roy
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Friday, July 17th, 2020 AT 8:40 AM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,
I just send a message but not sure if it went through, please confirm.
Thanks,
Bret
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Friday, July 17th, 2020 AT 3:01 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Just this post. Nothing from before.

Roy
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Friday, July 17th, 2020 AT 4:14 PM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

This email did not go through earlier:

I added 12oz of 134a which should be a total of approximately 1.44 lbs of Freon and enough to kick-off the compressor clutch but it has yet to turn on. Is there a way to reset the system i.E. By disconnecting the negative wire? I switched the compressor relay with the horn, the horn worked with both and inspected the compressor fuse which appears good. The low and high side gauges read 100 psi, I have attached a picture for reference. I will test the pressure sensor next in approximately 30 minutes. A reminder, I know the compressor clutch turned on, not for long, last Saturday when I added Freon but it hasn't since. Let me what you advise next.
Best regards,
Bret
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Friday, July 17th, 2020 AT 4:28 PM
Tiny
ASEMASTER6371
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Okay, first, no to the reset. There is no reset.

Go to the diagram I posted in the beginning. See the ac clutch relay. Check for 2 power with the key on. There should be 2 terminals with power.

If there is, then you need to test for power to the pressure switches as well.

Check those and let me know.

Roy
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Friday, July 17th, 2020 AT 4:35 PM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

I am having trouble testing the clutch relay, the probes on the multi-meter are too large to insert into the relay slots, same with the pressure switch. I tried inserting a wire, same problem. Any suggestions?
Bret
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Friday, July 17th, 2020 AT 5:40 PM
Tiny
ASEMASTER6371
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Use paper clips into the terminals and then the probes to the paper clips.

Works very well.

Roy
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Friday, July 17th, 2020 AT 5:51 PM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

Great tip.

1. We jumped the pressure switch with a paper clip and the compressor did not kick on.
2. We then measured and had 9 V DC at the pressure switch.
3. We measured and had 10 V DC at the relay on both sides of the relay switch.
Per your websites instructions the next step is a pin to pin test.

Please advise.
Bret
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Friday, July 17th, 2020 AT 6:14 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay, your battery is very low. You need to charge it. There should be 12 volts at the relay and the pressure switch.

https://www.2carpros.com/articles/how-to-charge-your-car-battery

https://www.2carpros.com/articles/car-battery-load-test

When you install the relay and turn on the A/C, does the relay click?

Roy
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Friday, July 17th, 2020 AT 6:31 PM
Tiny
BWILKINSON05
  • MEMBER
  • 68 POSTS
Roy,

The battery (Interstate) is about a year old however the truck has been in my garage for approximately 3 weeks, except for last Saturday after I removed the blend door actuator and drove it to Advance as a test run. Other than that short hot trip, I have only run during testing so the battery may be low. The multi-meter maxed out at 10V, I will look for a different setting in the morning.

One question, I removed the driver side blend door actuator and have not replaced the part. Would not having one in the vehicle skew our tests? We may have a open circuit without the part in the vehicle which could explain why the compressor did not turn on when I jumped the switch.

Regarding the relay, I have not heard a click anytime we turned the A/C on or off. I will test in the morning.

Bret
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Friday, July 17th, 2020 AT 7:22 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
No the blend door being removed will not effect the operation of the compressor.

Roy
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Friday, July 17th, 2020 AT 11:21 PM

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