04 4.4 A/C Compressor Removal

[X5F]

Update! Pulled it all out again to fit the spacer in, it fell off many times into the various crevices whilst moving the compressor into place.

Finally got it all back together in the early hours of the morning.

Now I read something about not starting the engine it till it had some refrigerant in the lines anyone know why?

Will it set a code or cause re-gassing issues or anything else?

Anyone heard anything about the desiccant needing replacing after the system being open for more than 24 hrs? Should I worry about it?

[upallnight]

Originally Posted by X5F

Update! Pulled it all out again to fit the spacer in, it fell off many times into the various crevices whilst moving the compressor into place.

Finally got it all back together in the early hours of the morning.

Now I read something about not starting the engine it till it had some refrigerant in the lines anyone know why?

Will it set a code or cause re-gassing issues or anything else?

Anyone heard anything about the desiccant needing replacing after the system being open for more than 24 hrs? Should I worry about it?

If you don't want to replace the desiccant, just run the vacuum pump a little bit longer when you go to evacuate the system. The desiccant is there just to absorb and retain any moisture in the system. Running the vacuum pump longer will draw out any moisture in the system.

As for running the system without refrigerant, the low pressure sensor will kick in and disconnect the clutch from the compressor. If you don't pull a vacuum moisture in the system will freeze when the system is turn on.

[andrewwynn]

Also there are rules for how much oil to add based on what lines were replaced etc. I don't think any were. You are supposed to measure how much oil is poured out of the compressor and replace that much and an amount more like 10cc.

[X5F]

Interesting info about the low pressure switch, can it be bypassed? could it stop the compressor coming on when you are trying to recharge the system ?

I’ll make sure the lines are evacuated very well then.

No lines were changed so all the existing oil in there should remain, I did lose a small amount from the lines when moving the compressor out.

The replacement compressor had the lines attached and blocked so should be good to go.

I believe most refrigerant has the PAG oil in it when it’s recharged anyway.

[wpoll]

Just leave the A/C belt off until you re-gas it...

[andrewwynn]

the R134a i use usually has no oil, but i get the one with oil when i do a full evac, i'll put that one in first, to compensate for any oil that was lost when the R134a leaked out.

The compressor is not going to kick on without the low pressure sensor behind shorted. It's only job is to protect the compressor for engaging when there isn't enough refrigerant. Sometimes 'to a fault' (where you can't get the stuff in because the pressure sensor is not reading correctly; i've had to short a defective low pressure sensor or hot-wire the clutch to force a compressor to kick on when it didn't believe me that there was R134a in there).

Mechanically of course it's true you can leave the belt off until, but it's a pain to install a stretch belt that i think that engine uses, so it might be easier to install the belt before you put the fan and shroud back on. I would personally evacuate just before i'm ready to re-start the engine. I would probably now that i think about it, recharge before i bothered putting the fan back in just to make sure the system was working before i had the whole thing back together.

Oh; measure the resistance on the low-pressure sensor post evacuation and as you put in the first can of 'freon' ; If you don't see it click closed, (or if it was closed without pressure), then that needs to be fixed! (a stuck closed low pressure switch will kill your new compressor should the 'freon' escape

[upallnight]

Originally Posted by X5F

Interesting info about the low pressure switch, can it be bypassed? could it stop the compressor coming on when you are trying to recharge the system ?

I’ll make sure the lines are evacuated very well then.

No lines were changed so all the existing oil in there should remain, I did lose a small amount from the lines when moving the compressor out.

The replacement compressor had the lines attached and blocked so should be good to go.

I believe most refrigerant has the PAG oil in it when it’s recharged anyway.

A can of refrigerant, when connected to a system that has been properly evacuated, should provide enough pressure in the system not to trip the low-pressure sensor.

[andrewwynn]

Correct. Like I mentioned earlier, test the low pressure switch before filling to make sure it's not failed closed. If the switch is working it will close when you put in the first can.

[X5F]

Final update!

Drove around for a couple of days without pressing the compressor button on and took it to the shop to be re-charged. I didn’t change any o-rings as they all looked good. I had the system open for a little over a week and didn’t change the deodoriser either.

They pulled vacuum first and then did a leak test on the system & then added 8ml of pag compressor oil and added 450g of R134a.

The result is nice cold air conditioning again!!! Very happy it’s finally over and hope this thread helps others.

[upallnight]

Originally Posted by X5F

Final update!

Drove around for a couple of days without pressing the compressor button on and took it to the shop to be re-charged. I didn’t change any o-rings as they all looked good. I had the system open for a little over a week and didn’t change the deoderiser either.

They did a leak test first and then pulled vacuum on the system & then added 8ml of pag compressor oil and added 450g of R134a.

The result is nice cold air conditioning again!!! Very happy it’s finally over and hope this thread helps others.

Thanks for the Update Mate.