Andy Kay

Got new AC lines and fittings on Monday. Filled w/ 4 cans freon. Blew @ 20 degrees. Drove from Houston to Dallas. Tuesday no AC. Fan blows. Hoses are dry. No yellow dye. Can hear clutch engage when key turned one click. Compressor is fairly new. Any ideas?

ivangene

coffee worked

no idea on A/C - its a mystery box to me

wwest

Blew @ 20 degrees.

Too low, 'way too low..!!!

Anything below ~40 and the evaporator will quickly freeze up given the slightest level of humidity, let along TX.

race911

I'm going from memory here, but isn't the system only supposed to take about 30oz? And this is an R12 system? What are the head pressures? You shouldn't see 20 degrees F at the outlet, the thermostat should have taken over to prevent the evaporator from icing over.

ron mcatee

Turn the thermostat to halfway or lower and adjust from there. 20 degrees is freezing up the coils. You would do well to get 38 degrees. Water freezes at 32 degrees and I think you have is a freezing of the condensation which blocks any air movement. Happened to me once and that's what solved my problem. Gotta melt the ice before any thing can happen. Let us know what you find.

Andy Kay

Couldn't believe it either-20 degrees at the AC vent all the way home. Been using the same mechanic for years. He installed the new hoses, flushed condenser, evac 'd system, added 3-4 cans of R134. Blew cold. Now both high and low are hot to the touch. Haven't checked evap in smugglers box or front condenser for leaks.

Oil pressure sending unit just died. Key in...turn one click... guage pegged at 5

ivangene

its like the car that just keeps giving



(troubles)

Andy Kay

Thanks for your help!

AC Update: The hose that runs to the front evap in the smugglers box had been spliced right near the passenger side rear axle. Zims found the leak, tightened both fittings at the splice and added 1.75 lbs of R134 freon. Now blows 34-36 degrees while driving. Thought they said the pressure was 275 over 40.

whalebird

Those numbers are plausible and quite good for R134. Those pressures roughly translate to the temperature of the system: high pressure=condenser temp, and lo pressure=evap temp.

Andy Kay

Car hasn't been driven since 4/21. Just drove the 911 to the bank. AC reostat (**** on the right) is turned counter-clockwise ie OFF Fan controller (**** on the left) is turned clockwise one click. In other words, I'm trying to get some fresh air, not AC. Within 5 mins the vent temp is 20 degrees...again.

In the mean time, my Druck Press guage is now pegged at 5+. Going to Zims on Friday for a new guage. I don't think the AC and Druck have anything to do with one another. Over the last two years, I think I have replaced all the AC components except the reostat. Any suggestions? Any idea where I can get the reostat for a 79 Euro. Pretty sure the AC is aftermarket. thanks

race911

Likely the switch isn't working. If aftermarket, then probably a generic part. Easy enough to just pop the engine lid and see that the compressor is staying engaged. (But 20 degree air tells you as much.)

Oil pressure gauge pegged at max is either an open or short at the sender (can't remember which, it's been so long!). Not the easiest to get to the switch on the front of the engine, but a simple, simple fix.

rusnak

On the AC, the temp probe is probably not inserted into the evaporator, or is broken.

The oil pressure gauge sending wire is probably bad or disconnected.

Andy Kay

Race911,

Thanks for your comments. I thought the reostat might be bad since I hear nothing while turning from the switch from left to right. Zim's has the part in stock for the Druck Press gauge for less than $50. Finding a new reostat is more difficult.

If the compressor is staying engaged and the temp drops to 20 degrees, do you think I may be damaging some part of the AC system?

stahwille

Is that 20 deg F or 20 deg C? Just kidding... However confirm temp gauge by droping into glass of ice water . Many analog temp gauges can and need recalibrated! If so hold flats on bottom of gauge, and turn top as needed. Other wise ck temp probe at evap. for kinks etc.. Heck watch it freeze in real time w/o wood / carpet blocking air and VIEW.. Best of luck Stahwille

wwest

Well, first of all that really isn't an A/C "reostat", it's a capillary tube/bulb.

COMMON POINT OF FAILURE.

The far end of the tube is (should be) "embedded" in the cooling evaporator vanes. The tube is filled with a liquid which has a high expansion ratio with rising temperature. As the liquid cools due to A/C operation the A/C "reostat" opens the A/C compressor clutch control switch.

When you turn the fan on even slightly that enables the A/C compressor switch circuit so the compressor will ALWAYS run at least at some relative minor level unless the sensor temperature is below ~50F.

Sounds to me as if the capillary tube/bulb control system is TU.