PrerYDoG

Okay - I have a part in the mail that is the motor that controls the flap for turning on/off my floor vents (Thanks Ians!). Here's what I have left:

1#: My top vents (on top of dash) won't turn off. If I move the slider I can hear a motor actuating, but the vents don't turn off. I'm guessing that the rod that pulls the flaps has come off the motor, but I don't know where this motor is...anyone have any clue?

2#: A/C is still pretty darn warm. Here's the issue. I have 134A and my hoses for pressure check don't fit the hoses on the compressor. When my dad and I filled it up last we put in 2 cans, but then the compressor started cutting on and off (kind of on for a few seconds or a minute, then would click off real quick and back on). Now, when it was doing this my dad said it was the compressor kicking off because it was too full, but I think it was the compressor kicking off because the car was overheating. He drained freon back out of it, and it stopped doing this, but again, the car was also no longer overheating.

My question here is two fold (or maybe three fold). One - my sight glass still shows bubbles. Does the bubble method work with 134A like it does with R12 (i.e. - should you NOT be seeing bubbles). Q2: Does the compressor have an auto-kickoff feature if pressure is too high, and Q2A: Does the compressor have an auto-kickoff feature if the engine temp gets too high?

3#: When I turn the **** to adjust from hot to cold in the car, the motor that twists the flap does not always actuate. It will move if I turn it to full hot, or full cold, but any "in-between" temps it just sits there and looks at me dumb. What is causing this? I know the motor is good (hooked it up to the floor slider switch), so it's either the temp switch, or something in between...any suggestions here?


TIA

Mark

PrerYDoG

Just got my part in from Ians. Will install it here tonight or this weekend.

Any suggestions on any of the above? Follow up questions, comments, concerns, good jokes, dirty jokes...?

gordyboy

After a fill my compressor did the same thing, cutting in and out. I borrowed a set of hoses with guages and it was obvious that the pressure was too high. I bled some out and everything worked fine afterward.

PrerYDoG

Okay, found a problem with #1, I found page 393 of Volume 3 of the porsche manuals has a diagram of whats going on. I found the motor (I can BARELY see it) that control the top vents. It moves, but there is NOTHING connected to it to move...so it just kinda is there for looks (and weight) right now. I need to find the things to hook it up to.

83na944

#2, Q1 You can't use the sight glass as a diagnostic when you put R134a in the system.

Did you change out the drier and pull a vacuum on the system?

A full charge of R134a is supposed to be 860g on a late 944. That should be a little less than 2 cans.

I don't think there is a high pressure switch on the system. The switch on the line going to the drier is a low pressure switch, at least on the early models it is. Not sure about the late models.

And I don't think there is a cutoff switch for engine temperature. Again I'm not sure about the late models.

PrerYDoG

No - I didn't do a change out of the drier. This wasn't a conversion, it was a pre-existing conversion, I don't know what the PO (Damn those PO's) did. If the site glass is a bad indicator, then I'm probably about right (or a little high yet) on the freeon.

Okay - edit to a previous post - Everything is hooked up properly to my top vents (at least from the motor side), I still get air though through them. Here seems to be the cause - Even when I have my Fan set to OFF, the fan is still running on LOW. WTF?

83na944

So you were just topping off the system? Then you're probably too high. You really need gauges to figure out what's going on.

PrerYDoG

Damn...didn't want to have to buy new gauges to fit this one vehicle. I'll try and get ahold of a set. What pressure did you fill your system to?

83na944

I think you charge by weight. If everything is working ok, it should probably be about 30-40 psi on the low side and 180-240 psi on the high side depending on ambient temperature.

I've read that if you overcharge with R134a, it won't cool well. Not sure why.

I think you should get at least a 20 degree drop. Did you measure the temperature?

PrerYDoG

No. Haven't had a really good day that I can measure it (seems like every chance I get to actually do that piece, it's cool and rainy anyway...Like today).

PrerYDoG

Bump - Still looking for ideas/help/support.

83na944

Mark,
Are you sure that the heater is off? I understand that late models sometimes have a small part that breaks and you end up constant warm air flow. The ac would have to work against that warm air.

Sorry I don't know much about the late models.

Kevin Baker

Steve is right on, there is not a high pressure cut off (although with a conversion to 134 there really NEEDS to be). With the fan switch off, and the dash vents open, and with the "recirculate" off, you should get a small flow of outside air as the car moves. That may feel like the fan is running, but it isn't. The refrigerant fill capacity is by weight, not pressure, however Steves pressure sugesstions are correct. R134 at 30F will have a pressure of about 30psi. This reading should be on the low side of the system.

PrerYDoG

Yeah, I'm positive that the fan is running. With the car off (i.e. - sitting in my garage), and the fan off, vents open, and recirculate off, the fan is moving, and there's a good bit of air flowing through the vents.

I'll get a pressure check on the system, I may be a little over full.

The constant warm air-flow problem is the infamous "heater clip", which I just fixed several weeks ago, and I know that it is okay.

Thanks for the suggestions guys.