AC Problems

[Laysan_A]

Hi Everyone!

I inherited my moms 89 Grand Marquis around Christmas this year. The air isn't working and I don't know what the problem is (I'm desperately hoping it doesn't need a new clutch or compressor). Nothing but hot air.

Looking through her paperwork, she had it converted a few years ago, and every year since she had it in to her mechanic for some kind of ac service - usually just some fresh refrigerant. I tried to recharge it, but the clutch won't engage (the face of the clutch pulley remains stationary). I jumped the plug of the low pressure cut-out (according to this image here: http://www.grandmarq.net/vb/attachme...4&d=1193052226 ). It was located on the same can as the low side charging nipple, down and to the right - right?

When the plug is jumped the engine idle changes, but the clutch remains still. The heater and blower work fine, so it doesn't appear to be a fuse. I'm not sure how to troubleshoot this. Someone mentioned a direct line from the battery to the clutch, but I don't read wiring diagrams well and there are two wires into the plug at the top of the clutch. Which do I run the hot wire to?

I hope someone can help me work this out. If it's the compressor I'm not sure what I'll do - perhaps just buy a smaller surpentine and bypass it - but I'd like to know.

Thanks!

[sly]

check the WOT or AC relay. It may be fried.

[Laysan_A]

Hi Sly. Thanks for getting back.

Uh...What's the WOT? All I'm getting is Web Of Trust...lol - guess I've been spending too much time on the computer. Also, I'm afraid I don't know where the ac relay is located. All I have is a Haynes and they've really gone downhill in recent years. I'm pretty sure there's no picture or description of the ac relay - although it does ID a general block of them, if memory serves.

I'm REALLY not good with electrical...(sorry about that).

[sly]

Wide Open Throttle relay. It may be marked AC relay. It's in the driver front corner. I don't remember which relay it is. There's 3 relays under the black plastic holders mounted there and one is fuel pump, one is the engine computer relay, and one is the AC relay. The relay down on the tab is the horn relay.

The WOT relay disengages the AC clutch when the pedal is on the floor since high RPM tends to nuke compressors.

[Laysan_A]

Cool. If they're marked I shouldn't have a problem.

If I may, as I said I'm not good with electrical, can I go over what I'm thinking is the correct procedure to test a relay - just in case I'm missing something important?

Please forgive me - I don't recall the correct numbers for the posts.

I should check the no power closed switch for connection with no drop off. Then I should connect the switch to the battery and verify 12v at the now closed post (I'm assuming they're just a single switch). That should do it - right?

[sly]

they're not marked, but here's a diagram... (should have searched this earlier to post, but meh... here ya go)

[Laysan_A]

Thanks Sly!

[Laysan_A]

Okay, this was kind of an odd experience because I wasn't sure about anything I was doing. I wasn't sure I had the right relay; I wasn't sure I knew which post was which; I wasn't sure if anything I did was really what was supposed to be done.

I think I got the right relay: It's in the same place as the image Sly provided (I think). Though the wire colors didn't match the diagram I had from Hanes, in the aggregate, comparing the colors of all three relays to each of their diagrams, this one seemed closest to the ac wot relay, and the others to theirs.

Once I got the relay unplugged I discovered it wasn't labeled correctly. Instead of having the standard 30, 85, 86, 87A, 87 numbers it was numbered in sequence from 1 - 5 ??? Anyway, I think I got it worked out - you can check it out in my images (in case they disappear, I believe 1 is 85, 2 is 86, 3 is 30, 4 is 87, and 5 is 87A).

Checking for completed circuits with a meter I found a connection with some impedance between pins 1 and 2, which seems proper for a coil. There was also a connection between pins 3 and 4, which I think is wrong, but which I don't understand. I'm probably mistaken, but I assume a bad relay would just stay open. I might have thought this was 87A, except that pin 5 had no wire to it at all.

I connected positive and negative leads from the battery to pins one and two, and at first I heard the hoped-for click, but things got confusing quickly. I checked for a connection between 30 and 87 but couldn't find one - but it's possible I was checking pin 5, not realizing yet that it was an empty slot (and thus likely 87A), but I'm not entirely sure because I decided to switch the polarity on 1 and 2 and when I did there were sparks (yeow!). I switched them back real quick and there were more sparks - and smoke! If it wasn't fried before...

So, on to the plug. As expected, slot 1 (-) and slot 2 (+) produce 12v. No other slots produce any current (???). It doesn't matter whether the car is running with the air on and the low pressure limit switch jumped. I checked the two fuses mentioned in my owner's manual for the ac and both were good. So there must be a problem upstream somewhere?

On other thing I tried. I unplugged the wires from the top of the ac clutch and connected them directly to the battery - very quickly and gingerly. I got nothing

Here's an image of where the relay came from:


Here's an image of the plug-end:


Here's an image of the relay posts (look closely and you can read some of the numbers):


Here's an image of the wire side of the plug. The colors weren't much better in real life.


So, I've ordered a replacement relay from O'Reilly's, but I'm concerned about the lack of current to anything but the coil. I don't expect it will fix anything. I'm also more than a little concerned that the clutch may be bad.

Any suggestions?
Any hope?

[Laysan_A]

Yeah, sorry about this. For some reason freeimagehosting is placing a url to some proxy service in their bb links. I really apologize. I've been trying to correct it but finally gave up. My bb code is really rusty - and never very good anyway. I was busy putting url= into the links when I ran out of time and was barred from any further edits. Unfortunately, the thumbs alone are pretty useless.

Laysan

I'm going to just put the links here, anyway:

This is where the relay came from:

http://www.freeimagehosting.net/cybbu

This is the plug-end:

http://www.freeimagehosting.net/l1lq1

This is the relay:

http://www.freeimagehosting.net/iarbz

This is the wire end of the plug:

http://www.freeimagehosting.net/i3ydt

Again, I apologize for my inability to get the images to work properly...

[sly]

you should be able to upload pictures to this forum directly. Click on the paperclip in the post window toolbar after clicking "GO ADVANCED" below the quick reply box.

You might be right about having a dead clutch since the direct battery check didn't do anything. Those are a bit of a bugger to swap and need snap-ring pliers.

[Laysan_A]

Hello again.

you should be able to upload pictures to this forum directly. Click on the paperclip in the post window toolbar after clicking "GO ADVANCED" below the quick reply box.

Ah. I didn't try the attachment tool (don't really know how it works). I tried the Insert Image tool and it wouldn't accept my files, either by url or directly from me. I don't know why.

Any idea why I wasn't getting any current through any of the plug terminals except the coil ones?

You might be right about having a dead clutch since the direct battery check didn't do anything. Those are a bit of a bugger to swap and need snap-ring pliers.

That's bad news...

Are you very sure that direct power (one positive, one negative) to those terminals would start a working clutch?

Can the clutch actually be changed without evacuating the entire system?

I really appreciate your help on this, Sly.

[sly]

The clutch can be changed without touching the rest of the system, but you need to know how to go about it. There will be shimming involved to get the new clutch spaced properly (new clutch comes with the shims). The biggest pain is just getting the snap rings off to get the clutch removed. The clutch is an electromagnet. If you have access to an ohm meter, you can test the resistance. If it's about 3 ohm, it's not the clutch. If it's way more or below 1 ohm, the clutch is dead.

[Laysan_A]

Good news. My clutch is fine!!!

(Thank God! I surely didn't want to have to replace it.)

I spent the afternoon reading through even more ac posts, and I found one where someone (I don't remember who it was now) placed a pos. wire from the battery to the striped wire's post on the clutch and a neg. wire from the battery on the plain black wire's post and the clutch started working. That, and this excellent post, http://www.grandmarq.net/vb/showthre...itioner+clutch in which Gadget lays out the specifics of the wiring from the low pressure cutout to the WOT relay to the clutch helped me to feel better about what I did yesterday, and just better understand the system. However, on my system I believe the wot relay is normally open rather than normally closed (as Haynes also shows).

Anyway, I got to thinking that maybe I was jumping the gun. Yesterday, while I was working on the relay, an acquaintance stopped by to ask me what I was doing and he was the one who suggested jumping the clutch to the battery and he was also the one who attached the clips (they're kind of a tight fit). It occurred to me that I was about to undertake a major hassle and I hadn't even double checked my findings. We were so concerned about maybe putting the wrong wire in the wrong place that neither of us really checked the connections. So, I went out and redid it, making sure each connection was tight, and voila, the clutch spun like a top. I've rarely been so pleased.

I put in all the 134a I had (got to about 17 at 68 degrees), and the air out of the vents was blissfully cold.

So, I was thinking that maybe both the relay and the cutout switch are bad. That would seem to me to explain why jumping the cutout switch plug (it shows 12v, btw) did nothing, and perhaps why there was no power on any of the relay connectors excepting the coil. Except that I tested the terminal with the cutout switch jumped, and that should have allowed the current through...

I got a new relay. I'll put it in and go from there. Let me know what you think.

[sly]

if the relay doesn't fix it, check that there's 12V to one of the pins on the pressure switch. Simply jumping that connection should engage the clutch when the rest of the system is working.

if you still don't have power, there may be an issue with the AC controls.

[Laysan_A]

Well I went out and plugged the new relay in and turned on the engine and air. The compressor spun right up. I began adding r134 to bring it up to pressure. I was trying to get the last of one of those large cans into the car and it was going slowly, but the air out of my vents was just above 37F. Pretty good! Unfortunately, after a while the compressor cycled off and didn't come back on again. The vent temp. got up to 80F before I shut it down.

It's always something, isn't it? I'm going to go back out and start it up again. If it runs I'll finish recharging (ice was forming on the accumulator - is that a problem?) and see if it happens again. If it doesn't run I'll check the power at the clutch, jump the low pressure switch and recheck the power at the clutch. If that doesn't point to a bad low pressure switch, maybe there's a bad connection between low pressure switch and the clutch. I may have to consider the possibility that something might be frying relays too, I guess.