meracus

hello chaps

I have a 987s with climate control, last year I took the car to my local garage to regas in an attempt to make the car aircon work ice cold
they did regas, a couple of weeks later the car was not blowing cold air, it was blowing air but just not cold enough by a large margin ... I would describe it as tepid .
so I thought maybe the FCU is leaky
I took my car to reputable Porsche specialist in the UK for some other work, I had a big scratch on the bumper and I thought I repaint it, and since the bumper is off, maybe we should do the ac this time
3 days later the garage calls and tells me there's nothing wrong with the ac and nothing needs doing, we regassed and test for leaks ... it's not leaking! I thought great, i did tell them my story though
picked up the car, tried the ac, cold ( not ice cold )
fast forward 3 weeks, tried the ac ...... guess what? tepid again, I feel like a mug
anyone have any idea
regards Andre

billwot

If there are no leaks, then it's likely the system is contaminated (moisture).

A qualified shop can purge, flush, pull a deep vacuum, then recharge.

meracus

thanks squire
is that so ? when moisture gets into the system , it stops blowing cold ?

badabing

I'm not an AC expert but i would do the purge flush and refill as well as replace the "dessicant".

It would have been nice also while the bumper cover was off the give the condensers and radiators a good cleaning (blow out debris).

Find yourself a good auto hvac specialist (not necessarily a Porsche specialist as there is nothing unique about the hvac system) and they should get you sorted.

Someone who knows how to test the system, high pressure side, low pressure side, etc.

GregWormald

I had the same issue with the new air con in the house. They sorted it under warranty.
They couldn't find anything immediately wrong so they drained the system, checked with high pressure hydrogen (I think that's what he said), no leaks--all was fine, re-gassed, and the air then came out at 2°C. It's been great all summer.

TMc993

If your system is leak free, your condenser coils are clean and free of debris and your compressor is functioning properly, the symptoms you are seeing could be caused by moisture contaminating the refrigerant, too little refrigerant or too much refrigerant. Keep in mind that you generally can't just "top up" refrigerant like you can oil or engine coolant and overfilling is just as bad as under-filling.

The proper procedure is to evacuate the system, pull a vacuum to factory specs, then refill the refrigerant to factory specs using the proper gauges to measure both the "high" and "low" side pressures while running the engine at factory specified RPM. As stated above by badabing, it would be a good idea to get an automotive HVAC expert to go through the entire system, evaluate and correct any issues they might find and bring everything up to spec. Otherwise, you'll be chasing this problem repeatedly.

meracus

hi
i have spoken to the garage this morning and they state that they have flushed the system prior to regassing, ( didn't explain to me in detail )
what the said is that they hold the vacuum for 3 minutes and their diagnostics came as no leaks
now they said to bring the car and they will check again more thoroughly as there might be a tiny leak that they cant spot unless they check every pipe etc .......... am I just being given the run around ???? I willing to give them the benefit of the doubt since they offered to do for free but if it's just a waste of time ill look for a specialist instead
the garage has an excellent reputation in the UK
thanks, chaps

Libast

When I test for AC leaks I test for vacuum for 30 minutes. That way even tiny leaks can become apparent. 3 minutes seems too much like a spot check.

Also if they used any sort of dye in the refrigerant, the leak will be instantly known with a UV light.

SpyderSenseOC

If the system is full of refrigerant and not contaminated and the compressor is operating normally, you are likely looking at an expansion valve issue (restriction of flow) or a problem with the temp blend system (actuator not able to fully open or close a door or the computer not telling it to do so). That's my 2 cents.

billwot

Not nearly enough. The leak check is just a secondary aspect of pulling vacuum. The primary function is to boil off any residual moisture. Vacuum should be pulled down to ~ 98 micron (29.5 in/hg) and held for at least 30 minutes.

billwot

billwot

SpyderSenseOC

This guy's problem is not a leak. It's not blowing cold "by a large margin" by his description. And it's not blowing cold immediately after an evac and recharge. Only a massive leak would cause it to blow warm right after an evac and recharge and a leak that big would be hard bordering on impossible to miss. I get all the debate about what a proper evac is but it's misplaced here. IMHO.

billwot

1) If a deep vacuum is not reached and held, there is a liklihood of residual moisture in the system.

2) All it takes is for a tiny drop of moisture to freeze and block the expansion valve.

3) That's a complete system blockage, the system basically becomes inoperative.

(state licensed HVACR engineer)

SpyderSenseOC

Anything's possible. But I still doubt it's a leak or moisture in the system. Repeated attempts to evac and recharge would likely not leave the same drop of moisture at the expansion valve and block it over and over. I'm not HVAC engineer. But I do frequently stay at Holiday Inn Express and I was a dealer tech for a long time and have never (serviced at least hundreds of auto a/c systems) experienced the situation you describe with moisture repeatedly blocking an expansion valve. Not saying it couldn't happen. Just haven't seen it.

My reading is that this system NEVER blows cold air no matter what, fully charged after several discharge/evac/charge cycles. I'm leaning expansion valve defect or ducting issue (software or mechanical). I've been wrong before.