AC diagnosis needed
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New Member
Joined: Jan 2019
Posts: 8
From: Carrollton, Tx
AC diagnosis needed
Hello all! I have an 08 Fit and the compressor is not engaging and the condenser fan also does not come on. I put gauges on the high and low. Low was 65 and high was about 70. Tested the relays in the box by the battery and they both clicked when I jumped power to them. I pulled the pressure switch on the high line and tried jumping it to no avail. Don't see one on the low line anywhere. I pulled the electrical plug to the compressor and was getting 4.5 volts with the key on whether or not the engine was running. Zero with the key off. Jumped from the battery to the plug going into the compressor and got Sparks and the wires got hot but no click on the clutch coil. That was with the engine off but I don't think that should matter. Am able to turn the compressor by hand and it feels like moderate resistance but turns well . I'm guessing the clutch coil is bad but the 4.5 volts confuses me. What say you?
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New Member
Joined: Jan 2019
Posts: 8
From: Carrollton, Tx
I I might do that yes. Did you know where the low pressure switch is? The only sensor IC with wires coming out of it connected to a pressure line is on the high pressure side
Member
Joined: Jan 2019
Posts: 36
From: Fishers, IN
There is only one pressure switch...I'll see if I can find a wiring diagram
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New Member
Joined: Jan 2019
Posts: 8
From: Carrollton, Tx
Oh ok. Well I tried jumping it and it didn't affect anything. With it plugged in I got the 4.5 volts reading in the 2 outer wires of the 3 going to the compressor. As I now understand from stuff I read this morning, that is the go ahead signal from the pressure switch to the coil relay. I need to test again and see if the center wire of the 3 is hot with 12v. If it is then the coil or the coil relay is bad. If it isn't then it's electrical problems before it gets to the compressor. I'm also going to hot jump the relay by the battery and see if that activates the coil. I read that also this morning. I'm new to this if you can't tell. 😐😁😀
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New Member
Joined: Jan 2019
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From: Carrollton, Tx
Thanks for the wiring diagram. I pulled the connector on the power wire to the clutch coil and hooked up the battery to it and nothing happened. I'm certain the clutch coil is bad. I really triple checked it and used my multimeter to make absolutely sure I had power in the hot wire. The question now is, if, through puppy like exuberance and lack of fear, I ran a hot wire and a ground wire into the 2 wires that connect to the compressor near the rear, what would that do? The wires got hot immediately. Is that a low pressure switch built into the compressor? Is it worthwhile now to try and just change out the clutch coil or should I be safe and do the whole compressor under the assumption that I destroyed it? SMH .Learning
Member
Joined: Jan 2019
Posts: 36
From: Fishers, IN
Thanks for the wiring diagram. I pulled the connector on the power wire to the clutch coil and hooked up the battery to it and nothing happened. I'm certain the clutch coil is bad. I really triple checked it and used my multimeter to make absolutely sure I had power in the hot wire. The question now is, if, through puppy like exuberance and lack of fear, I ran a hot wire and a ground wire into the 2 wires that connect to the compressor near the rear, what would that do? The wires got hot immediately. Is that a low pressure switch built into the compressor? Is it worthwhile now to try and just change out the clutch coil or should I be safe and do the whole compressor under the assumption that I destroyed it? SMH .Learning
Did the connector come from the compressor and have a Wht/Blu and Blu/Wht wires? The wiring diagram is your friend...there is a box around a thermal protector and a/c clutch in the diagram...those would be your compressor connectors. According to the diagram, there is a thermal protector in the compressor...if gets hot, shuts off. It’s only a switch. You shouldn’t apply voltage there, that’s why it got hot. You basically connected the positive directly to a negative without any fuse to blow and protect the wiring.
On A/C....9 out of 10 times it’s either a leak or compressor wore out and is no longer compressing enough to bring the high pressure up enough. Coils can fail also but electrical failure is pretty uncommon.
So you have 65 psi on the low side with car off/compressor not running, right? (low is always the larger sized lines, high pressure is small size lines)
Unplug the connector going to the clutch and put a volt meter on the 2 wires to measure voltage. Don’t apply any power to anything...that’s risking damage. Just measure voltage on the vehicle side of the connector and turn vehicle to run position and turn a/c on...let me know what happens. You may need a helper but only measure voltage of those 2 wires. You should see a change with a/c and turned off.
Last edited by FitG8Guy; Jan 12, 2019 at 04:11 PM.
New Member
Joined: Jan 2019
Posts: 4
From: Fresno, CA
Sounds like you already got it covered.
on pin 3 (white/blue) it should be 5v w/ AC on
Coil resistance to ground should be 3.15 to 3.45 ohms at 68 degrees F, if it's extremely high or open, you have a bad coil or thermal protector
on pin 3 (white/blue) it should be 5v w/ AC on
Coil resistance to ground should be 3.15 to 3.45 ohms at 68 degrees F, if it's extremely high or open, you have a bad coil or thermal protector
Thread Starter
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New Member
Joined: Jan 2019
Posts: 8
From: Carrollton, Tx
Whoa cowboy! Lol
Did the connector come from the compressor and have a Wht/Blu and Blu/Wht wires? The wiring diagram is your friend...there is a box around a thermal protector and a/c clutch in the diagram...those would be your compressor connectors. According to the diagram, there is a thermal protector in the compressor...if gets hot, shuts off. It’s only a switch. You shouldn’t apply voltage there, that’s why it got hot. You basically connected the positive directly to a negative without any fuse to blow and protect the wiring.
On A/C....9 out of 10 times it’s either a leak or compressor wore out and is no longer compressing enough to bring the high pressure up enough. Coils can fail also but electrical failure is pretty uncommon.
So you have 65 psi on the low side with car off/compressor not running, right? (low is always the larger sized lines, high pressure is small size lines)
Unplug the connector going to the clutch and put a volt meter on the 2 wires to measure voltage. Don’t apply any power to anything...that’s risking damage. Just measure voltage on the vehicle side of the connector and turn vehicle to run position and turn a/c on...let me know what happens. You may need a helper but only measure voltage of those 2 wires. You should see a change with a/c and turned off.
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