Hello All,

Last year I converted to the 134 freon from the R12. I seems not cold enough (hot/cold air mix). I checked the low/high side pressure and they seem normal and the system is full of freon. The compressor is working.
Is there anything else to make it produce cold cold air?

Has anyone fitted a PRO-COOL sold by Tweeks?

Thx
GP

 

Hey GP,

What is your center vent temperature vs. ambient temperature? This what ultimately determines if your A/C is cooling as well as it should. You can measure the temperature by sticking a pencil thermometer in the center dash vent.

Per the shop manual, when measuring center-vent temperature, you're supposed to:

-park the car where it's not subjected to sunshine
-clean the condenser
-close the sunroof, doors and windows
-set the temp. control to blue dot
-set the blower to 4
-set the sliders all the way to the right
-open all dashboard air outlets
-measure ambient temperature
-rev the engine to 2000 RPM and let the A/C run for 2 minutes before taking the measurement.

A somewhat more convenient, accurate-enough-for-our-purposes method, is to just take the center-vent temperature while driving down the freeway, instead of trying to rev the engine for 2 minutes. However, this method will mask an out-of-service condenser fan.

Speaking of the condenser fan, have you verified it operates, as I mentioned on another thread this morning?

You may find that your 964's A/C is running per factory specs, but not as cool as your other cars. Even the cheapest domestic car will have better A/C than a 964 or 993. But, at least it works, something you can't necessarily say about earlier 911s.

Best of luck, and let us know what you find.

 

Hi Randall,

How do you check if the condenser fan is working?
and how do you clean it?

Thanks
GP

 

Hey GP,

In essence, the condenser is little more than a radiator with refrigerant instead of coolant inside. I would first shine a flashlight up into the ground-facing grill to look for any big pieces. When I cleaned my own, I took didn't do anything fancy. I didn't even remove the mudguard to gain better access. I simply sprayed a garden hose up through the grill as best I could.

Incidentally, if your system is working correctly, you can actually improve performance (lower center-vent temperature) by spraying water across the condenser. A neat trick I saw the A/C shop use. Not that it's practical for everyday driving <img border="0" title="" alt="[Wink]" src="wink.gif" /> , but interesting to know.

Checking to see if the condenser fan works. It should come on automatically when the A/C is turned on. If not, or if it cycles on and off in fast-speed, you have a problem. You can evaluate the relay, fan and ballast resistor using tips at this DIY:

<a href="http://p-car.com/diy/fan/" target="_blank">http://p-car.com/diy/fan/</a>

 

Just to elaborate a bit more on accessing the condenser, its in the driver side (LHD) front corner, roughly behind the indicator/fog lights. If you really want to 'go to town' in cleaning it then you will need to remove the front wheel and undo about 10 philips screws to remove the front part of the inner wheel liner. That shouldn't take you very long (10 to 15 minutes maybe). Just don't remove the condenser itself otherwise you'll obviously loose all the gas.