AC Help needed. Yes i searched.
06-02-2011, 10:57 PM
#31
Electron Wrangler
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Sliding the temperature higher wouldn't work - the AC (when on) is always on full - the temperature control just uses the heater core to warm up the pre-chilled air..
You also can't permanently wire like that because the AC clutch will be engaged even when the car is off... (so you'd need an ignition supply).
For a temporary fix you need to connect the upstream side of the freeze switch to either an ignition supply (difficult in the engine compartment) or via a switch & fuse to the jump post and remember to turn it off... emergency only...
Alan
You also can't permanently wire like that because the AC clutch will be engaged even when the car is off... (so you'd need an ignition supply).
For a temporary fix you need to connect the upstream side of the freeze switch to either an ignition supply (difficult in the engine compartment) or via a switch & fuse to the jump post and remember to turn it off... emergency only...
Alan
06-02-2011, 11:19 PM
#32
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Thread Starter
Sliding the temperature higher wouldn't work - the AC (when on) is always on full - the temperature control just uses the heater core to warm up the pre-chilled air..
You also can't permanently wire like that because the AC clutch will be engaged even when the car is off... (so you'd need an ignition supply).
For a temporary fix you need to connect the upstream side of the freeze switch to either an ignition supply (difficult in the engine compartment) or via a switch & fuse to the jump post and remember to turn it off... emergency only...
Alan
You also can't permanently wire like that because the AC clutch will be engaged even when the car is off... (so you'd need an ignition supply).
For a temporary fix you need to connect the upstream side of the freeze switch to either an ignition supply (difficult in the engine compartment) or via a switch & fuse to the jump post and remember to turn it off... emergency only...
Alan
I did the switched and fused power to the upstream side of freeze switch. It should only be for a few weeks until I get a new relay in my head unit and/or my custom head unit from Paul/Hans is installed. Either way it will keep me cool in the mean time and I have a nite on the dash to remind me to turn off the switch when I shut the car off. Switch is lighted under the hood too so when I come home at night and raise the hood to let the heat bleed off ( always do this in summer to reduce heat soaking everything under the hood) I'll see the lighted switch is green and remember to switch it to red.
06-03-2011, 12:07 AM
#34
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Thread Starter
06-03-2011, 12:14 AM
#35
There ya go. Thumbs up.
06-03-2011, 12:22 AM
#36
Rennlist Member
Thread Starter
I forgot to add in the video, it is plugged in on the upstream side of the freeze switch so I have that protection as well as the low pressure switch. Here's another question. Since I switched to R134, and the 93 (IIRC) and later sharks came with R134 with a high pressure switch as well, how do I incorporate a high pressure switch into my setup once I get the head unit functioning again.
06-02-2013, 12:05 PM
#37
Jeff,
Look close around the oil dipstick and find a single black wire. There should be a connection very near the dipstick tube on the front of the engine. With the ignition switch on and the A/C on, there should be 12 vdc on the black wire. If there is, the problem is at the compressor.
If there is no power on the black wire, trace it forward from the connector to the pressure switch on the receiver/dryer. Again, with ignition and A/C on, there should be 12 vdc on both sides of the pressure switch. If there is power on only one side, the refrigerant level is probably low. If there is no power on either side, hook everything back up and go to the Central Electrical Panel. Find Plug E (plugs are alpha left to right, no I plug) Find the black wire in Terminal E11.
Terminals are arranged:
15 25
14 24
13 23
12 22
11 21
That means E11 is the bottom left terminal on Plug E, which is fifth from the left end. Again, ignition and A/C on, there should be 12vdc on the black wire. If not, go back under the hood.
Remove the rubber seal across the back of the engine compartment, and very carefully remove the very fragile thin black plastic shield at the base of the windshield. Find the A/C anti-freeze switch, a silver block about 2"x2" with two wires and a metal tube. Ignition on, A/C on, check for 12 vdc on both sides. Power on one side shows a faulty switch. no power shows a problem in the HVAC system in the dash.
Let us know what you find. Be very verbose and very precise.
Look close around the oil dipstick and find a single black wire. There should be a connection very near the dipstick tube on the front of the engine. With the ignition switch on and the A/C on, there should be 12 vdc on the black wire. If there is, the problem is at the compressor.
If there is no power on the black wire, trace it forward from the connector to the pressure switch on the receiver/dryer. Again, with ignition and A/C on, there should be 12 vdc on both sides of the pressure switch. If there is power on only one side, the refrigerant level is probably low. If there is no power on either side, hook everything back up and go to the Central Electrical Panel. Find Plug E (plugs are alpha left to right, no I plug) Find the black wire in Terminal E11.
Terminals are arranged:
15 25
14 24
13 23
12 22
11 21
That means E11 is the bottom left terminal on Plug E, which is fifth from the left end. Again, ignition and A/C on, there should be 12vdc on the black wire. If not, go back under the hood.
Remove the rubber seal across the back of the engine compartment, and very carefully remove the very fragile thin black plastic shield at the base of the windshield. Find the A/C anti-freeze switch, a silver block about 2"x2" with two wires and a metal tube. Ignition on, A/C on, check for 12 vdc on both sides. Power on one side shows a faulty switch. no power shows a problem in the HVAC system in the dash.
Let us know what you find. Be very verbose and very precise.
06-02-2013, 12:56 PM
#38
Also can someone post a pic of the freeze switch? I searched and could not find one. I am starting to think mine is removed from the car. I see the expansion valve, I see another block with wires going to it but that block appears to only have electrical leads has no line going to the evaporator.
06-02-2013, 01:49 PM
#39
OK I believe I have found the AC freeze switch. It is not really what I expected. Basically it is just a thermometer with no freon running through it. That threw me on off a little. I still have not figured out where I am suppose to be checking power at the control panel. I get no power at all at the freeze switch or low pressure switch so that is the next place I need to check for power.
06-02-2013, 02:34 PM
#40
Instructor
Also can someone post a pic of the freeze switch? I searched and could not find one. I am starting to think mine is removed from the car. I see the expansion valve, I see another block with wires going to it but that block appears to only have electrical leads has no line going to the evaporator.
06-02-2013, 03:12 PM
#41
Have read thru Dwayne's HVAC compressor relay repair in the DYI section. He describes a comprehensive troubleshoot of the systems: https://rennlist.com/forums/928/6788...re-w-pics.html
06-02-2013, 09:22 PM
#42
Chronic Tool Dropper
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Can't do what you describe. It will leave the clutch powered even with the key off. Some suggested that you can add a relay near the jump post, with the relay coil wired to the freeze switch.
Read the write-up about adding a relay to the head unit. There's full diagnostics, and the fix is better and easier than a rube Goldberg add on at the jump post. IMHO
Read the write-up about adding a relay to the head unit. There's full diagnostics, and the fix is better and easier than a rube Goldberg add on at the jump post. IMHO
06-02-2013, 11:03 PM
#43
I did read that already and am going to try to take the unit out this week and refresh all the vaccum lines at the same time. Thanks again Dwayne. At least now I know that I have a system that is holding a R12 charge. I still do not have AC again but I feel like I am getting a better understanding of what needs to be done for the long term.
06-03-2013, 10:43 AM
#44
Race Car
Did you try disconnecting both wires from the anti-freeze switch and jumpering them together? Sometimes the anti-freeze switch fails, so I would rule that out before pulling the HVAC head unit.
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
06-03-2013, 01:31 PM
#45
Thanks Dan, I did test the wires at the freeze switch and have no power on either side. I still have not figured out how to test at the control panel though. I just do not see a black wire at E11. I have two red wires in that spot.