A/C blowing fuse.. Any idea?

[nelsonmxmarc]

Car; 1993 HCR32 GTST Type M
Fairly new compressor unit.
R134A Swapped system.
Diagnostics check on EVAC gives a clear read, no problems.
ECU Reset.
Wires have been pulled to check for shorts, seems okay.


So this is what happens; I'll start the car, let it run for a moment then hit the A/C switch. The compressor will kick in, motor will shudder from the current draw (like normal..), then the fuse will blow. All within 3-5 seconds.

When i first bought the car, the previous owner told me the A/C no longer worked after they installed the DRL's but thats absolutely nuts since the wiring for the DRL's takes ACC power from the wiper motor, runs along the firewall and to my headlights.

During the first week of ownership, i put in a new fuse (thinking it was 15a) and ran the A/C. It ran flawlessly for 2 days then blew. Now i'm obviously using a 10 A fuse but replaced with either size makes no difference anymore.

I realize a common issue is that that windings go in the compressor unit (SAU). Changing them isnt TOO difficult however it is a days job, and since it may not even be the issue, i'm just wondering if anyone has had a similar issue with a quicker / easier fix.


Also, i've got a ZEXEL pump off my 92 GTST parts car. It wasn't converted from R12 to R134A so i'm just wondering; since the label on the pump says the refigerant is R12, can i use it to pump R134a on my 93 GTST, or is the pump no longer usable?

Thanks in advance!! This problem is really wrackin my brain!

[linedriver]

i would check all the wiring first to make sure there isnt any broken insulation or anything. if all else fails, you can create a new circuit for it, and if that fuse blows, it might be the windings inside the compressor.


also, since the pump isnt supposed to be used for R134a nor is the entire system for that matter, you might find the system leaking refridgerant faster then normal since the molecules are smaller. i wouldnt say its bad or anything, but it might not be good for the pump either

[nelsonmxmarc]

Good call on the leak, ill have to check that out. Thanks for the quick response!

I was even thinking if the system is TOO full, would that cause the circuit to break? I've heard both sides of the story from many mechanics and im just about ready to quit the DIY and get the system checked lol.

Any wiring diagrams available for the R32 compressor unit / A/C unit that could facilitate finding a short or hooking up a separate circuit?

It's such a PITA too, being that its deep in the abyss of the RB20 cavity.. ughhh

[linedriver]

over filling would probably result in a decrease of cooling efficiency, it wont cause a fuse to blow in any way. if there was such a device to prevent overfliling, it would be a pressure activated switch which cuts the circuit, not blow the circuit.


unfortunately i dont have a wiring diagram for the AC of an R32, but there is only 3 wires going to it anyways. one of them requires +12V to activate the clutch, so it might be easier to feed it power through that wire. also, by the sounds of it, i think a wire might be broken in the interior of the car probably from a stereo install or something. unless someone did a hack job on the wiring in the engine bay, then there shouldnt be a short in the circuit anywhere. the fuse in the inside of the car activates the big relay in the engine bay.

[nelsonmxmarc]

YES! Okay we're getting somewhere..
Since it blew cold air intermitently i would have to say it's a short somewhere, and you did bring up the fact of a haggard stereo install.. Well this car was nothing short of haggard when i picked it up.. No wires were soldered, all taped. Wires jammed in and around things, too short, spliced into weird power / acc terminals etc..

What wires are there behind the center console, or dash area that could cause such an issue? Basically im looking to go from the EVAC to the fuse box and look for traces of damage there?

Thanks a lot for the help! That really gave me something to think about because to be honest, it was a dirty mess in there. I'll take a look when i put in my new gauges.

[linedriver]

just start at the climate control panel and work your way out. or work your way from the fusebox.


my AC had a problem as well, but it didnt blow a fuse or anything. what happened with mine was that the climate control unit sent the signal to the relay to turn on, but it wasnt turning on. it got the signal, so i just added a wire to complete the circuit, so now my AC works with the OEM controls.


if you get stuck finding the short, and want to use AC, just create a circuit and add a switch inside the car. that way, you dont have to find the short anymore and you get AC. itll probably take much longer to find the short anyways

[nelsonmxmarc]

Ill check it out! Thanks for the incite.

if you get stuck finding the short, and want to use AC, just create a circuit and add a switch inside the car.

I'm sorry for my noobism but to run an aux switch from the AC compressor, i'd have to tap into the 3 wires from the compressor; 1 being pwr, the other being ground.. This is where i get a bit confuseled. The 3rd is from relay?

So basically run a direct wire from power on the compressor unit with a spliced 10 a fuse to a switch, the negative the same minus the fuse. The third...?

Lol so confused!

[linedriver]

not sure what the 3rd wire is for. im pretty sure that the ground is just an additional ground, but the body itself should probably work just as good. the fuse itself is to protect the relay. regardless of how little a relay needs to be activated, it should still be from a fused source

[nelsonmxmarc]

Thanks man, ill check er out tomorrow!

[ck_chino]

i had the same issue with my gtr
if u look at the fsm, it says that the proper ohm for the windings for the comp shud be about 3.5 ohms.........

what you should do is go directly to the connector of the a/c comp
there will be 2 connectors one with a single wire and one with 2 wires
avoid the 2 wire connector and you want to measure the ohm of the single wire connector.......so disconnect it and with ur multimeter.....measure from there and the other to the body of the car. it shud say approx 3.5 ohms.........any lower and u are drawing too much current


ie mine was 0.8ohms follow the I=V/R formula and you find that its way over the rated 10amps

if thats the case which i prefered to be rather than chase wires, you gotta change the coil

hope what i said helps

[nelsonmxmarc]

Awesome man, really appreciate it! That will definitely help me rule out the compressor.. I've got the wires labeled from the pump up by the washer fluid reservoir so it shouldnt be too hard to grab a reading there.

Thanks for the resistance too; i checked all over the place last night for info!

Marc

[nelsonmxmarc]

Alright so, it turns out im getting about 1.3 ohms.. I'm assuming this is TOO low, thus my problem is in fact the windings?

Have you done an in-situ replacement of the windings or just swapped the whole compressor?

I've got a spare zexel laying around off the parts car that might be worth checking i guess.

[nelsonmxmarc]

Okkkk to post ontop of myself again lol...

My spare compressor has a resistance of 4.1 .. I'm going to tinker more with the one on the car now until i have run out of solutions then just swap the windings and see how she goes!

[BrianV8]

I gutted mine haha weight reduction

[nelsonmxmarc]

Ughh you're sick! I cant handle those hot humid days in the rain! I have no choice but to blast the fan and even though it says 18 degrees, it's def like 35 lol.