Another 944 AC Question Heeelp!
 

Found the low side input. Checked pressure. Gauge shows 44. The air coming out the vents is barely cool. Car was updated to R134 July 07 with New condensor, compressor, dryer, low and high pressure valves, etc. Anyone have any idea what might be wrong? clutch on compressor engages. stays engaged-but air barely cool. Could the problem be an overcharge? If so, could I just let some out on the low pressure side?

Thanks

Is the compressor clutch kicking on?

Yes clutch engages on compressor

From very recent experience...

If the shop put too much AC oil in---beyond 5-7 oz---it will settle in the bottom of the condensor and cooling will deminish.

If the shop put too much R134a in---more than 2-12oz cans or about 70-80% what R12 uses----the system will not work and may turn into a heat pump and blow in hot air.

BUT

I am going to say the expansion valve is clogged.

On the late 944s it requires a dash removal to change the expansion valve and "O"rings. This from my research usually is not changed due to the hours and hours of labor.

When a system is converted to R134a and had as many major components changed as yours, the lines, condensor are flushed and the receiver dryer is replaced. You also mentioned the compressor and condensor.

The evaporator should be flushed but not the expansion valve which is connected to the evaporator. So it is not flushed.

The expansion valve fills with thick oil and clogs.

On early 944s and 87 & 88 924S cars it is a one hour task to drop the evaporator and take off the expansion valve. When I did mine recently, the "O" rings on the expansion valve fell apart and had black oil in the tube.

A shop can determine what is clogged.

BTW- guage readings should be "about" 30 psi LOW and 230 psi HIGH depending on ambient temp 3" from condensor for R134a

GL
John_AZ
1988 924S + 1987 924S

A clogged expansion valve would usually cause high pressure on the high side and low pressure on the low side, wouldn't it???

Does your compressor ever kick off after it initially kicks in or does it just keep running? There really isn't enough info available at this time to make a diagnosis, but it sounds like your compressor may be on it's way out. You'd need to know the high side pressure to be able to make a more informed diagnosis. Harbor Freight sells a manifold gauge for $50 and a venturi vaccum pump for $15 (you'll need an air compressor to run it). The manifold gauge will allow you to diagnose the problem (i.e., determine the high side pressure) and the pump will allow you to properly evacuate the sytem before recharging if you do have to replace something.

I'll be on the fence until I know what the high side pressure is. 44 on the low side is high when the compressor is engaging, but not ridiculously high, depending on the ambient temperature. The problem may be because the heater is fighting the evaporator.

Pinch off the inlet side of the water line to the heater core with some vice grips, put a rag over the hose so as not to damage the rubber and check both high and low pressures. Did it cool better?

Is the recirculation door inside the air box functioning? Broken heater clip?

With the additional information of "Puddle of water on the ground under the center console" my post above is way off and mattdavis11 knows best.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/492818-ac-problem-944-more-info-your-diagnosis.html#post4845381

Still learning...the hard way at times.

John_AZ

your low side is ok.

as mentioned earlier, check for possible hot air mixing with cold air which evens out as no cooling effect.

Thill944,

Please stop starting new updated posts, it is hard to follow your progress and offer new advice.

You have some very talented people who want to help you. You are loosing us with new posts.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/493172-944-air-cond-question-continued.html#post4848150

John_AZ

thill944

Back to your last post:

944 Air Cond Question-Continued

--------------------------------------------------------------------------------
Quote
"Continuation-It wasn't the heater clip. Checked it tonight. The air coming out the vents is barely cool, probably just regular air uncooled. Checked the temp of the air coming out the vents. Around 80 degrees. When I turn it over to heat, heat works fine. Updated to R134 July 07 with New condensor, compressor, dryer, low and high pressure valves, etc.--by a Porsche shop. When I run the AC a puddle of water appears on the ground underneath the car about where the console is located. I guess something, somewhere is getting cooled. Are you supposed to see anything in little round sight glass? I see nothing running or not. My low side pressure is around 40. Anyone have any idea what might be wrong? clutch on compressor engages. stays engaged-but air isn't cool.

I don't know if I did wrong but I held the needle in on the low side and let it bleed down to around 20. It was just air coming out I think. The air coming out wasn't wet. I then put a can of 134 in the system (AC and car running) to bring it up to 35. Still no change in temp.

I know if it to an AC shop I'm gonna get a big hit in the wallet. Really can't afford that. Have any more suggestions? Thanks"

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I will review the heater clip idea. I would just like to post a link to www.944online.com tech section but until they upgrade the site now in progress, you have to sign up and become a member to view. This is the link:

http://www.944online.com/cgi-bin/forum/forum.cgi?board=944tech;action=display;num=1187187 877

There are 2 types of heater clips. These pictures credit to www.944online.com.


http://forums.pelicanparts.com/uploa...1250945503.gif


http://forums.pelicanparts.com/uploa...1250945531.gif


http://forums.pelicanparts.com/uploa...1250945550.gif

If all the clips are ok and the sliders on the control work you need to check the vacuum lines and vacuum tank.

There is a vacuum tank on the firewall. Mine is tucked by the battery and some are mounted in front of the battery. It looks like a tall beer can laying on its side-black or green. Follow the vacuum lines and the "T" connections. Without this tank the vacuum assisted vent door will not open. You may have a cracked tank.

GL
John_AZ
1988 924S + 1987 924S