AC compressor not running

OK I think I found the antifreeze switch. Is this the relay with a capillary line and two wires? checked the leads and no power on either one with AC on full. Did have power on the low pressure lead. Will try putting power on the clutch connector located on the single black wire that runs next to the oil dipstick. Must be the small relay on the control board. Am I going in the right direction? Any comments?

Walt

"Went to this site did not see the tips and links on the left."

They are there...
Go to: www.928gt.com
At the bottom of the home page, click on the appropriate entry for the browser that you use.
In the black block on the left, find +928 Tips/Links and click on the +.
Find +Wally's World (928 Tips) and click on the +.
Find The HVAC System and click on it.
Print the paper, and read it at your leisure.

On the '86, current flow to the compressor clutch is:
From the small relay in the HVAC head unit on a violet/yellow wire to the Evaporator Thermoswitch (freeze switch); from the freeze switch on a lilac/yellow wire to Terminal G21 (lowest terminal on the right side of Plug G); from there behind the Central Electric panel to Terminal T13 (3rd terminal up on the left side of Plug T); from T13 on a black wire to the Low Pressure Switch (on the Receiver/Dryer); from the Switch on a black wire to Terminal 9 of the 14-terminal connector; from Terminal 9 on a black wire to the compressor clutch; from the compressor clutch to a ground connection.

If you have no power on either side of the freeze switch (it is not a relay, but a thermal switch that opens at 32 deg F or lower, closes above that) with the AC and the blower on, the most likely problem is the small relay or a connector in the circuit. If you have no power at the freeze switch, you will have no power at the low pressure switch or the compressor. There is also a fan switch on the receiver/dryer - that is probably where you are seeing power.

Remember that voltage isn't power. It is possible to have 12+ volts on a meter, but not have sufficient power to operate the compressor clutch.

AC clutch still not pulling in. Did fine the site on Wally's world about the AC. Replaced the small relay with larger one with no problems. This is what I get:
1. 11.74 volts at the freeze switch with engine not running.
2. 13.72 volts with engine running.
3. Connect to wire going to low pressure switch volts drops to 0.24 volts at freeze switch with engine running.
4. Connect battery power to wire at freeze switch going to low pressure switch (with freeze switch disconnected from controller) clutch will pull in.
5. Have 11.94 volts at fuse for AC and engine not running have 13.72 volts with engine running.

Have decided to keep the AC and ditch the 928.

Any 928 shops in Charlotte, NC that can digest my AC issue?

Walt

If I understand your explanation of your problem

Ok it sounds like you may have a near broken wire or a highly corroded connection on that wire that goes to the low pressure switch.
Think of it like trying to start your car with a speaker wire from the battery.
You proved it by jumping to the switch with another power source.
Do you have a head lamp or signal light that you can use to check for power at the fuse,
(with two wires attached to the bulb) and then you will find where the power stops and where you still have it.
A test light will only show that you have some power but not draw enough current like a headlamp would, thats why I recommend you use a load large enough do draw some power.

If I connect battery power through the freeze switch and through the low pressure switch and the clutch will pull in. Just will not pull in when connected to the controller, which has the new relay.

I have 13.78 volts (engine running) at the freeze switch but when I connect to the clutch voltage drops to 0.24 volts. I even ran a wire direct to the clutch bypassing the freeze and low pressure switches and had the same issue of the voltage drop.

The only way to get the clutch to pull in was to connect directly to the battery source.:confused:

Walt