A/C: no power to compressor and condenser fan

[schoward]

AC has worked great for 9-10 years. 911sc 1981 us spec with factory a/c.

Yesterday I hit it on and evaporator fan runs as usual but no compressor kick in and no condenser fan. Evaporator fan runs at all speeds but no power at condenser fan or compressor. Rotated temp knob and nothing.

Tried swapping out round black relays and they all appear good. No popped fuses at first glance.

Any tips on where to go next? Relay in smugglers box?

Thanks,
Scott

[86 911 Targa]

Originally Posted by schoward

AC has worked great for 9-10 years. 911sc 1981 us spec with factory a/c.

Yesterday I hit it on and evaporator fan runs as usual but no compressor kick in and no condenser fan. Evaporator fan runs at all speeds but no power at condenser fan or compressor. Rotated temp knob and nothing.

Tried swapping out round black relays and they all appear good. No popped fuses at first glance.

Any tips on where to go next? Relay in smugglers box?

Thanks,
Scott

Have a look & rotate fuse #2 on the fuse panel.

The relay closest to the front of the car runs the condenser fan.

Then check the relay in the smuggler's box.

Then the connection at the compressor. (green wire).

Good luck,

Gerry

[Discseven]

Scott... I've experienced no system power at all and it was a stuck relay in the smug box. A few taps on it and power on. So... if you have evap fan power I would guess it not being relay in smug. Have also had compressor shut down. Don't recall if front blower went down when this happened. Diagnosis is: #1) jump the solid green and green/white wire connected to the thermostatic switch... if power on, bad thermo switch. #2) If you have a pressure switch, jump that. Not sure that that would effect your front blower but would definitely shut down your compressor. (Problem I experienced was a pressure drop and pressure switch worked as it should. Disregard "Risky" note.)

[kuehl]

Karl,
When are you sending the royalties check?

[Discseven]

Originally Posted by kuehl

Karl,
When are you sending the royalties check?

Monster you created was waiting for you to show up You send me check. (Frankenstein need scarf --- AC too cold now. )

Credits: you did send me schematic... but who decided jumps? The noob!

FYI Scott, Kuehl = ultimate Porsche AC wisdom. Listen to him. Be sure to follow instructions... or you'll get beat up.

Am outtahere now --- West and his tag team killer company are surly due any moment now.

[SilberUrS6]

Originally Posted by Discseven

Am outtahere now --- West and his tag team killer company are surly due any moment now.

I'm on point for this op.

Nice Freudian slip, there. ("Surly" as opposed to "surely" - LMAO).

[schoward]

[QUOTE=Discseven;8251213]

FYI Scott, Kuehl = ultimate Porsche AC wisdom. Listen to him. Be sure to follow instructions... or you'll get beat up.

Am outtahere now --- West and his tag team killer company are surly due any moment now.[/

I'll start with fuse removal/inspect and check temp switch and A/C relay. Thanks all for getting me started and have a nice day

I do like the Kuehl products though.

[schoward]

Update : all fuses fine, compressor connection fine, and then replaced the a/c relay which did not nothing.

Frustrated, I thumped my finger aggressively on the ac temp switch knob and compressor clicked on and condenser fan came back to life.

Need to dig into this switch now. I replicated the issue a few times so switch seems to finally be tired.

I have read about the poor fitment of the new ones. Aside from fit, how hard are these to swap out? Do I have to remove the old and resnake the new temperature sensor wire or can I keep my existing and connect to new switch?

[wwest]

Originally Posted by schoward

Update : all fuses fine, compressor connection fine, and then replaced the a/c relay which did not nothing.

Frustrated, I thumped my finger aggressively on the ac temp switch knob and compressor clicked on and condenser fan came back to life.

Need to dig into this switch now. I replicated the issue a few times so switch seems to finally be tired.

I have read about the poor fitment of the new ones. Aside from fit, how hard are these to swap out? Do I have to remove the old and resnake the new temperature sensor wire or can I keep my existing and connect to new switch?

High grade SILVER solder flowed onto the contact points will bring the switch back to life for another 10 years.

[wwest]

Alternatively:

In '58 the USAF supplied me with 2-3 of these for burnishing/filing relay contacts on B-47's and KC-97's.

For many years after I always kept a few in my field service kit.

Use one to "clean up" the switch contacts and then add a relay to indirectly power the clutch circuit. Switching such a high current indicative load as is the clutch coil is a "dirty" business, best left to an easily replaceable relay contact pair. While you're at it the addition of an LED light to indicate compressor cycling rate might be a good idea. But keep in mind that the inductive "kick" upon opening the inductive clutch involves a LOT of power, so a resistor/LED, POWER LED, is advised

Switch Contact Burnisher/File [BURNISHING TOOL 1/4 INCH] : Pinball Magic, Your Pinball Resource

[Mhead]

AC on a 72T...can't get power to the solenoid side of the relay in the smuggler's box. If the relay is manually closed, the compressor clutch and fan work as they should. Just can't get the fan speed knob to actuate the solenoid.

Any suggestions?