Day trip to inland SoCal - needed air and got nothing but hot air. Figured perhaps just low on R134A so bought a can of AC Pro. Hooked it up and got nothing. Reading instructions it looks like the compressor may be shot. Instructions said to add 1/2 can to see if compressor would engage. Nothing. That little black disc on the front of the compressor is supposed to engage and spin, right? It doesn't! What's a new compressor going to cost? Could it be something else?
AC Blowing Hot
- Thread starter Brentbba
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Yes the "little black disc" (your compressor clutch) needs to 'engage' in order to turn the compressor. You'll need to apply 12 volt power directly to it (via the connector) to see IF it is even operable. No point going any further until you know that.
When was the last time you used the A/C and was it cooling correctly then?
I just had the same thing happen to me. Turns out I was very low on refrigerant. I took it to a place that was certified and they put a vacuum on it. I guess I was low by 2 pounds. I had just replaced my compressor about two years ago but I was worried that it wouldn't work. Turned out fine after adding refrigerant.
- Thread starter
- #5
I tried adding refrigerant, but without the compressor engaging, couldn't. The instructions even stated that if the compressor didn't engage, try adding 1/2 a can - system wouldn't accept any! Guage was pegged way above the green 'fill' category, so not sure what's going on. I hate the thought of going to a dealer. They'd just want to replace the compressor! I think I may find an independent AC place to test it like you did.
From what I have learned from my recent AC work is that the AC system is rarely low on refrigerant for no reason. If it is low, it is because there is a leak in the system somewhere. It may be small, but will eventually leak out again. Best is to run uv dye through it, find the leak, fix and refill. It was surprisingly easy to do with the free/rented AC tools from autozone to diagnose and fix the problem. My 2 cents.
I'm in the middle of redoing my AC. So far Mud and @flintknapper have me on the right track. There are all sorts of threads, which makes it confusing. @alia176 has a great thread on removing the cooling unit. I'm going to try and condense everything I learned and read into a single thread. Once you know the condition of the compressor, just go for it.
I flushed all the lines and evaporator yesterday. The evaporator took a lot of time. All I'll say is I'm glad I had real goggles flushing the evaporator. Since I couldn't finish assembly yesterday, I'll just reflush it all next weekend. I am glad I'm replacing the condenser. I've considered replacing the evaporator too since it is such a pain to flush.
I flushed all the lines and evaporator yesterday. The evaporator took a lot of time. All I'll say is I'm glad I had real goggles flushing the evaporator. Since I couldn't finish assembly yesterday, I'll just reflush it all next weekend. I am glad I'm replacing the condenser. I've considered replacing the evaporator too since it is such a pain to flush.
Just went through and replaced my compressor with a Denso unit from RockAuto, and replaced the dryer and expansion valve while I had it all apart. Dropped the vent temps somewhere between 10 and 15 more degrees from where it had been at, so overall pretty happy. One thing though - if your engine temp is too high it will not allow the A/C to cycle on. Have you tried working the A/C in the cool of the morning to see if it will run then? Another easy diagnostic is to get the gauges and check against the FSM.
Good, then we have established that everything in 'system' has worked at some time in the past.
If you want to find an independent shop, you might start here, MACS sets best practice standards for automotive A/C.
Nostradamus
SILVER Star
Most compressors are protected by low and high pressure switches that disengage the compressor if freon charge is too low (most common case) or too high.
To bypass the low pressure switch, unplug the connector and jump it to + on your battery. Do it with engine off so you can hear the clutch - it should make a pretty loud click. If that works, then leave the clutch connected to the battery and fire up engine and turn AC blower on hi, temp on coldest setting. Now you will be able to draw refrigernat into the circuit from the suction side of the loop. Once you have enough refrigerant in the loop, you can reconnect the clutch to the low press switch and you're good to go.
If you have a slow leak, you may have to do this once or twice a year. A bigger leak might be worth fixing.
I have an 85 FJ60 (R134A) and an 85 BWM convertible (R12) and I need to do this about once per year on the BMW and every other year on the FJ60. It's a one beer project, since I have the manifold gauges and a custom built jumper wire for the clutch and a bunch of R134A and R12 (getting R12 it a PITA - if you ever do major AC system work, switch over to R134A)
To bypass the low pressure switch, unplug the connector and jump it to + on your battery. Do it with engine off so you can hear the clutch - it should make a pretty loud click. If that works, then leave the clutch connected to the battery and fire up engine and turn AC blower on hi, temp on coldest setting. Now you will be able to draw refrigernat into the circuit from the suction side of the loop. Once you have enough refrigerant in the loop, you can reconnect the clutch to the low press switch and you're good to go.
If you have a slow leak, you may have to do this once or twice a year. A bigger leak might be worth fixing.
I have an 85 FJ60 (R134A) and an 85 BWM convertible (R12) and I need to do this about once per year on the BMW and every other year on the FJ60. It's a one beer project, since I have the manifold gauges and a custom built jumper wire for the clutch and a bunch of R134A and R12 (getting R12 it a PITA - if you ever do major AC system work, switch over to R134A)
^^^^^ This 'assumes' the reason the clutch won't engage is because of low system pressure! The trouble is....many folks have NO idea if that is the case or not. The 'correct' thing to do is put a set of manifold gauges on it. Far too many people just 'assume' the system is low on refrigerant, so off they go to get a can of refrigerant to 'pour in the cool' before knowing:
1. Current pressure (or lack of) of the system.
2. Condition of the compressor/clutch/AC circuit.
3. Whether or not they have any significant leaks.
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- #14
Thanks for the link - three shops listed reasonably close to me - one closed, owner died! Yelp reviews on other two are good...for what those are worth.
@flintknapper - Thanks for the layman's replies - very helpful!
Absolutely right. Where would it have gone if it wasn't that there was a leak somewhere? I'll give this a try.
$1.3k for the whole kibosh (compressor, drier, etc.) done by local shop...picked it up yesterday, fwiw.
- Thread starter
- #17
Dumb Dumb Dumb. Evidently when I replaced my headlight bulbs with LED's I knocked loose an A/C sensor plug located in the battery tray on the DS Side just above the low beam bulb location - thus no power to the compressor! All it took was plugging that back in!
Kudos to John at SD Trux for tracing down this little electrical 'issue'. R134A was just fine as is the clutch and compressor. She blows cold as ice again.
2 THINGS
1) Freon doesn't just "disappear" over days, months, years, etc. IF it's low on freon it's leaking somewhere.
2) don't just "add a can or two" unless you enjoy paying to have your stuff fixed "correctly".
If your not sure what your doing find a buddy that does, or take it to a shop. That way they can "draw down" the system, check everything, and set your system back up the CORRECT way. Then it will last another 25-30 years! Enjoy!
1) Freon doesn't just "disappear" over days, months, years, etc. IF it's low on freon it's leaking somewhere.
2) don't just "add a can or two" unless you enjoy paying to have your stuff fixed "correctly".
If your not sure what your doing find a buddy that does, or take it to a shop. That way they can "draw down" the system, check everything, and set your system back up the CORRECT way. Then it will last another 25-30 years! Enjoy!
- Thread starter
- #19
Marine7 - thanks, but you're late to the party. R134A was fine. It was simply an unplugged connector to a sensor that was shutting down the power to the compressor. 23 years and refrigerant was still fine, so no leaks in my system.
Dumb Dumb Dumb. Evidently when I replaced my headlight bulbs with LED's I knocked loose an A/C sensor plug located in the battery tray on the DS Side just above the low beam bulb location - thus no power to the compressor! All it took was plugging that back in!
Kudos to John at SD Trux for tracing down this little electrical 'issue'. R134A was just fine as is the clutch and compressor. She blows cold as ice again.
Brentbba, do you have a picture of the sensor? I have similar problem and I need to find this sensor. On a different note, I have a swapped LC with a 6bt in it. So, I don't know how much of the wiring is stock. It shouldn't effect any sensors, so I need to know where this sensor is, and what it look like some that I can track it down. Is this sensor inline between the AC switch and the compressor?
