GrannyWithGloves

2004 F150 - AC blowing hot air. Sometimes the first time I turn AC on from cold start (relatively speaking - in TX, 99 degrees outside, but engine is 'cold') I can get cold air for a few minutes, then it starts blowing hot air. I've replaced the blend door actuator - no luck, replaced the AC Clutch Controller relay switch - still, no luck. Refrigerant pressure is fine. I'm about to try to replace the thermostat, but before I climb in there and pull everything apart, thought I'd check here to see if there might be something else I should look at...

ProjectSHO89

Leave the thermostat alone, it shouldn't be a factor.

You need to clarify what you mean by "cold air for a few minutes, then it starts blowing hot air".

By "hot" do you mean that it actually goes HOT, as if the air is being heated by having passed through the heater core, or do you mean it is simply no longer being cooled in which case it would be ambient or a few degrees warmer than ambient.

If the former, you have an issue with the blend door function. If the latter, it's probably an issue with the compressor clutch. For a vehicle of that age and, assuming an original compressor, I always recommend checking the clutch gap first as excessive wear will cause your (presumed) symptom.

nrivera04

Check the gap of your compressor clutch. If you’ve had to replace the relay once already, it’s possible you have too much gap.

ProjectSHO89

The OP said that replacing the relay resulted in "no luck".

nrivera04

He said he replaced it again, meaning that it already burnt up at least once causing concern for an excessive gap. ...or at least that was my assumption.

ProjectSHO89

I interpreted the use of the word "again" to indicate that the second guess was no more productive than the first.

Unlimited HP

I would check the temperature of the low pressure (return) line. A/C pressure notwithstanding, if the temperature of the return line is not low (38-42F) than its the A/C system causing your problem. Whether that's low freon or clutch air gap is something you'll have to determine. If the low pressure line is cold then it's a temperature control issue. And whether that's a blend door or a thermostat control...well, you'll figure it out.

tlrtucker

^ This x 100. This guy repeatedly recommends this and it works. I had issues where my AC would work great, then go hot. Checked my compressor's gap and it was 3 times the acceptable gap. Literally takes 10 minutes to check and correct. Mine has worked great ever since.

RL1990

A 2004 in Texas; safe to say that old compressor is just tired and worn out by now. Time to replace it, you definitely got your money's worth out of it.

ProjectSHO89

There was no evidence presented that the compressor is "tired and worn out".

In any event, it appears that the OP is not going to return and follow up, so just let it die.