My A/C worked great up intill a week ago. I went and got some 134a stuff and tried to add it and the clutch is still not working and the can did not empty into the a/c unit. Last week I noticed it wasnt working so I left it on as I drove. A few miles later it worked and then it stopped. Now it doesnt work at all. I checked the fuse and its ok. The max a/c switch blows the fan at the speed its supposed to. Any other suggestions?
A/C clutch troubleshoot
- Thread starter Mark89coupe
- Start date
Hissin50 is the REAL expert on this AC stuff. But I can try and pass along what he did for me.
1. Check low pressure switch. Jumper it with a paper clip. If the clutch turns on then your low on fluid.
2. is the clutch spacing too high? Maybe the spacing is too high and it can't grab the plate?
3. See if you have 12vdc on the coil. If not see item 1.
4. If you have voltage on the coil, see item 2. It is possible the coil is open. Measure the resistance of the coil. If open, that's your problem.
Is your car a R134 system or the Older R12? If you mixed them then you got real problems. The R12 seals will shrink and create a leak...hence the low pressure switch. If you have a leak, you can add a tracer to try and find the leak and fix it from there.
JT can add much more to this? I'm sure I'm missing something.
1. Check low pressure switch. Jumper it with a paper clip. If the clutch turns on then your low on fluid.
2. is the clutch spacing too high? Maybe the spacing is too high and it can't grab the plate?
3. See if you have 12vdc on the coil. If not see item 1.
4. If you have voltage on the coil, see item 2. It is possible the coil is open. Measure the resistance of the coil. If open, that's your problem.
Is your car a R134 system or the Older R12? If you mixed them then you got real problems. The R12 seals will shrink and create a leak...hence the low pressure switch. If you have a leak, you can add a tracer to try and find the leak and fix it from there.
JT can add much more to this? I'm sure I'm missing something.
OK. I did a search and did what it said. I jumped the connector on the aluminum thing on the firewall. When I did that I heard a click. The test light would not stay lit. I reconnected the connector and would hear a click every 5 seconds. I traced the click to a relay looking thing under the mas air flow. Its on a bracket that is screwed into the fenderwell.
What do I do next?
I replaced the coil 6 months ago. The a/c worked fine till now. How would I find if its a open coil?
What do I do next?
I replaced the coil 6 months ago. The a/c worked fine till now. How would I find if its a open coil?
Id, thanks for the kind words bud. not true, but thanks. 
(how ya been? truck running good? house good?)
I am not able to follow what exactly is happening here (we dont know history on retrofit, if the system has proper pressure, etc), but i will toss out a couple cents worth or less.
the WOT relay is what is under the MAF/inlet tube. heat often kills the wiring or relay. the WOT relay will open the A/C circuit (kills the juice to the A/C clutch) when at WOT. otherwise, the circuit flows through the common and NC terminals (at non-WOT situations).
so when idling with a/c on, the clutch should have juice. if not, backprobe at the WOT relay to see what is missing. sometimes goosing the relay and wiring makes it work - that suggests bad wiring or relay.
this assumes that the low pressure switch is functional, the system has propler pressure and that the wiring is good (the wiring at the LPS can fry too).
to recap, juice goes from the LPS to the WOT relay and then to the a/c clutch.
good luck.
(how ya been? truck running good? house good?)I am not able to follow what exactly is happening here (we dont know history on retrofit, if the system has proper pressure, etc), but i will toss out a couple cents worth or less.
the WOT relay is what is under the MAF/inlet tube. heat often kills the wiring or relay. the WOT relay will open the A/C circuit (kills the juice to the A/C clutch) when at WOT. otherwise, the circuit flows through the common and NC terminals (at non-WOT situations).
so when idling with a/c on, the clutch should have juice. if not, backprobe at the WOT relay to see what is missing. sometimes goosing the relay and wiring makes it work - that suggests bad wiring or relay.
this assumes that the low pressure switch is functional, the system has propler pressure and that the wiring is good (the wiring at the LPS can fry too).
to recap, juice goes from the LPS to the WOT relay and then to the a/c clutch.
good luck.
unless you stand there with the hood up and rev the motor at the throttle linkage, you probably wont hear it (i have to hold them to feel it).
if you have power to the clutch, the WOT relay is at least passing current (the common and NC terminals are closed at rest). if the relay goes south, it probably would not kick off the a/c at WOT.
for me, no parts stores had them.
if you have power to the clutch, the WOT relay is at least passing current (the common and NC terminals are closed at rest). if the relay goes south, it probably would not kick off the a/c at WOT.
for me, no parts stores had them.
Stang8URMPRT
Active Member
I would stick my hand on it, cause if it turns on, it's gunna rip your hand off lol. If your clutch is turning on and off, on and off when on MAX A/C, that means you have low pressure in the system.. meaning you need to recharge it. But it's unlikely it just "evaporates" and more likely you are leaking it somewhere. I just did the whole R 134a conversion, and I know it's leaking.. cause about 2-3 days after... the AC is hot again.Mark89coupe said:
I hate a/c, and love it at the same time. 
How come I have power at the aluminum thing at the firewall(on off switch?) but im not getting power at the compressor? Does the WOT relay interupt it? I did go WOT a few days ago with the a/c on would that affect it?
What is making the relay click every five seconds?
WHat about inside the car at the switch. Is there something behind there I should look at?
What is making the relay click every five seconds?
WHat about inside the car at the switch. Is there something behind there I should look at?
to reiterate what i said earlier: you say you have power at the LPS (what you refer to as the on off switch, i think). do you have power out of the switch, or just into it? you need power out of it. from there the power goes to the WOT switch. it passes through the common and NC terminals (non-WOT) to the a/c clutch. did you goose test the wot relay wiring or at least look at it? you need to look at the wiring or check your pressure to know what is going on.Mark89coupe said:
good luck.
I have power at the lps harness.
I have power at the WOT harness.
I dont have power at the compressor harness.
I ran the same tests on my 97 explorer but there is power at the compressor.
Does this mean something happened from the WOT relay to the compressor?
I traced all the wires they all look good.
I also tested the conection where the compressor wire meets above the oil filter and there was no power there. Where do the wires go after they leave the engine bay.
I checked all the a/c vacumm hoses on the firewall and they all have good vacumm.
Whats next??
I also have pressure in the system, I got a special gauge to test it.
I have power at the WOT harness.
I dont have power at the compressor harness.
I ran the same tests on my 97 explorer but there is power at the compressor.
Does this mean something happened from the WOT relay to the compressor?
I traced all the wires they all look good.
I also tested the conection where the compressor wire meets above the oil filter and there was no power there. Where do the wires go after they leave the engine bay.
I checked all the a/c vacumm hoses on the firewall and they all have good vacumm.
Whats next??
I also have pressure in the system, I got a special gauge to test it.
you need to post specifcally and explicitly what wires have what reading under what conditions. saying that the WOT relay has power means nothing. it should have constant power, key-on power (coil), switched ground (on the coil. this only shows ground at WOT) and 12 volts out, unless the relay is energized (at WOT, which interrupts the power out to the clutch).
I am posting exactly what i do when i troubleshoot this stuff. grab a piece of paper and write down the color of each wire. i test them in different conditions to better diagnose things, but that is up to you.
do you see what i mean? all relays have constant power to them, so saying that it has power means nothing. one must have power and ground to energize the relay's coil and then note if there is indeed constant power to the relay and power leaving the relay. the entire dynamic should be tested. this will take less than 5 minutes with a DMM (a test light can latch the relay, which causes funkyness).
good luck.
I am posting exactly what i do when i troubleshoot this stuff. grab a piece of paper and write down the color of each wire. i test them in different conditions to better diagnose things, but that is up to you.
do you see what i mean? all relays have constant power to them, so saying that it has power means nothing. one must have power and ground to energize the relay's coil and then note if there is indeed constant power to the relay and power leaving the relay. the entire dynamic should be tested. this will take less than 5 minutes with a DMM (a test light can latch the relay, which causes funkyness).
good luck.
Ok. All I have it a testor light. I dont have something to tell me what volts I have.
On the LPS there are 2 orange wires and one green. The green shows power and the oranges dont.
On the WOT harness there are 4 wires. Red gives power. Orange stripe that is right next to the red has no power. There is a single orange wire that gives a very low voltage. The black wire has no power.
Hissin50- thanks for your patience.
On the LPS there are 2 orange wires and one green. The green shows power and the oranges dont.
On the WOT harness there are 4 wires. Red gives power. Orange stripe that is right next to the red has no power. There is a single orange wire that gives a very low voltage. The black wire has no power.
Hissin50- thanks for your patience.
no problem - this stuff is a pain to 'work on' from a keyboard and frustrating for those trying to help ya.Mark89coupe said:
the first problem is that apparently the wiring colors on your 89 are different than those on my 88. the way i see it, we are stuck at the LPS. when there is not enough pressure in the system (like ID said up front), the switch opens and wont let juice out, to go to the WOT relay or the clutch. there should be one power feed at the LPS (which you have, i think), but there should also be power out (to go to the WOT relay). i dont think you have that. so either the system is low on refrigerant or the LPS (at a min) is bad.
were it me, i would check the system static pressure (with a guage or have a shop do it - it takes about 30 seconds) or you can VERY BRIEFLY do what ID said and jump the LPS. if the system is low and you run the system (by jumping it) you can damage components. so this should only be done very quickly to see if the clutch locks up.
i would do that and go from there. it sounds like you might simply be low on refrigerant (has the system been converted to R134?). when you went to add refrigerant to the system, the LPS kept the clutch from engaging, which kept you from being able to dump the can into the system. if the system is low and you want to add a can (of like refrigerant - R134 and R12 are not compatible, nor are their oils, per se [there are oils which work for both]) you can jump the LPS, which engages the clutch, which allows your can to get emptied into the system. that is what people do when the system is too low to even cycle on. that might be all that you need.
good luck.
i have not changed a LPS, but have read about it. it should unscrew, IIRC, and come right out without much fuss (a tiny bit of refrigerant might come out, but not much at all - a quick hiss worth). then screw the new one in. that should do it.
good luck.
good luck.
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