AC not taking freon? 99 7.3 Jumped compressor

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Apr 24, 2023 | 03:49 PM

soopsoop

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Trailering

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AC not taking freon? 99 7.3 Jumped compressor

Vacuum pump is out ( which only operates blend doors , cruise control & 4x4 ( Im told )
there for only air is coming from defrost vents**

I jumped the compressor to keep it running while adding more freon to X out the possibility of Low R134A refridg

Seems the can is not getting empty at all ... Could I have another issue ? Do the blend doors need to be operating to function the AC ? Or will it just come out of the defrost area

Apr 24, 2023 | 10:12 PM

Kwikkordead

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From: Rio Rico, AZ.

The blend door doesn't have much to do with the function of the AC except to warm the air back up after it passes through the evaporator.
Do you have a set of AC gauges to test pressure?

Apr 24, 2023 | 10:49 PM

soopsoop

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ive got one of those cheaper gauges for the low pressure side . It seems to be in range or slightly over pressurized . I think there could be air in the lines? Trucks been sitting for a year. The compressor will go on an off contstantly unless I jump the low pressure switch ....
then it stays on .... I tried to refill the freon at that point and still no cold air. PSI seems good 35-55 low pressure side ... fluctuates as AC cycles

Apr 24, 2023 | 11:33 PM

udsuth78

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From: Ponca City, OK

Does the refrigerant line get cold directly after the expansion valve just before going into the evaporator box? Have you checked the gap on the compressor clutch? I don't remember the spec offhand, for some reason I want to say .080 but don't take my word for it. If it's to wide there is a shim between the hub and plate that can be removed to extend the life a little. For the system to get air in it it would have to have completely discharged. If that were the case you wouldn't get any cycling from the compressor, it would have to be jumpered until you got at least a can in the system. All the same if you suspect contaminates then likely best to have it evacuated so you can find and fix the problem. Oh and go to Harbor Freight and pick up their refrigerant gauge set. They aren't the greatest but they get the job done, and once you have they you can start charging your buddies beer for checking their ac systems.

Apr 25, 2023 | 04:45 AM

kenn_chan

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From: Yokosuka Japan

dumping all refrigerant is and then using a set of scales to add the correct amount is the best way of dealing with this. but you might have a bad drier, a clogged expansion valve or any of a dozen different issues to deal with. dump it once, vacuum it out, and then diagnosis it.

Apr 25, 2023 | 08:12 AM

Kwikkordead

Fleet Owner

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From: Rio Rico, AZ.

I've had more than one incidence where the high side switch gives up due to too many amps going through the tiny little pins on the connector. Repair procedure was replace the switch itself along with the plug assembly at the same time. I'm on the third one now.

Apr 25, 2023 | 11:40 AM

bigb56

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From: Arizona

Quote:

Originally Posted by Kwikkordead

If the high side switch was open wouldn't that prevent the compressor from running at all? If I had to guess, which is all we can do from our chairs, I'd say possibly a clogged orifice tube.