A/C is hurting idle and blowing hot air

[Stealthlead]

Unfortunately the A/C in my 91 Grand Marquis has gone out. I don't know to much about my A/C system so I'm kind of confused with where to start.

When the A/C is turned on (any setting) and the car is idle, it seems to draw a lot of power and causes the car to run very rough and kind of bump around. I'm assuming this is due to an old/bad compressor. In addition to that problem, when the A/C is on it only blows very hot air. I have no overheating issues (anymore) and the car used to blow moderately cold air a few months ago. I know a lot of you would suggest just cutting the A/C lines but it gets pretty hot here in Arizona. Also, in the winter time my car seems to do the exact opposite.. it takes about 20 minutes to blow hot air, lol. I was told this is due to an old heater core. The reason I bring this up is because I am wondering if this should be done in conjunction with the other A/C work stated.

I have a $500 budget for this project and the objective is to get the car to blow very cold air. I have a friend in the A/C industry who says he can get me R12 if I desire it and is willing to help me out as well. Any help is appreciated.

~Stealthlead

[Southern_Pride]

You probably need a compressor. Hook up some gauges and turn it on and see if it even does anything. Make sure you flush the lines. There some other parts that should be changed as well but I cant think of the names of them right now.

[Crownvicman289]

The way you describe it it does sound like the compressor is dying, my old truck would do this. It blew cold air, but the belt would chirp every time the A/C compressor clutch kicked on and you could feel the truck jerk as you were driving down the road in OD. I eventually had to quit using it because of this. Try turning the compressor by hand with the engine off and let us know how difficult it is as that's more than likely the culprit. You can then get the R-134A retrofit kit from Walmart and charge it yourself. Depending on what the junkyard gets for a compressor, and assuming you do the work yourself, you should be able to do this under $150 quite easily.

[1987cp]

Good thread - I was thinking a while ago of posting up with almost the same question. My A/C's been bogging the engine, and while it has been cooling since the R134 conversion last summer, it's not running efficiently enough even for the dryer canister to get cold like normally happens on a healthy A/C system. Convenient that I have a "spare" compressor that, if it still works, might be in better condition than the one I'm trying to use ....

You probably need a compressor. Hook up some gauges and turn it on and see if it even does anything. Make sure you flush the lines. There some other parts that should be changed as well but I cant think of the names of them right now.

What gauges? How? I have access to a set of normal commercial/residential gauges - is there an adapter that will let these hook to R134 ports?

Also, what do you mean by "flushing the lines"?

I've heard that the dessicant canister and something called an orifice tube should be replaced whenever opening up an A/C system ... and of course that it's got to be pumped down after closing it back up ....

[Stealthlead]

Hey guys, sorry for the late reply (Parties+work).

Anyways my Condenser doesn't seem to have a very smooth turn. Also, my Accumulator has always looked to be very old and is pretty rusted out. My friend is going to take a look at my A/C system and we'll try to pin point the leak. He is also certified to refill them so I'm set there.

Is it really best to get a used accumulator off of another merc? Also, I've read that somewhere along the A/C lines in my year model, it leaks a bit onto the frame and can cause rot and that specific line is rerouted. Is this a good time to do it and is there a specific guide on that?

Thanks for the help,

~Stealth

[86VickyLX]

The 'line' you're talking about is the AC evaporator drain, you have to make a line to route it away. Get a new accumulator, when they're open to atmosphere long they get moisture in there, and they're worthless. Why are you turning your condensor? :p You can get away with a used compressor. But you're limited to years, since they changed stuff in late boxes. I think (someone else verify) that the 1989 and 1/2+ compressors will work with your lines.

[gadget73]

last accumulator I bought was like 30 bucks. Not worth messing with used. Besides, like the man said, once they are exposed to atmosphere they are basically done for.

and yes, 89-91 compressors are what you need.

[Stealthlead]

Why are you turning your condensor? :p You can get away with a used compressor. But you're limited to years, since they changed stuff in late boxes. I think (someone else verify) that the 1989 and 1/2+ compressors will work with your lines.

Compressor*.

last accumulator I bought was like 30 bucks. Not worth messing with used. Besides, like the man said, once they are exposed to atmosphere they are basically done for.

and yes, 89-91 compressors are what you need.

something like this

http://www.rockauto.com/catalog/moreinfo.php?pk=814952

Any suggestions on picking a good used compressor from the junkyard?

Thanks for the help guys!

[86VickyLX]

If I were gonna get a compressor from the yard, first, it would be a system that's still charged with freon. That would indicate the seals are good. Spin the pulley, make sure that spins really nice, no grinding or weird feeling. Spin the clutch, see if that spins. It should have resistance, and should be pretty uniform while you turn it.

[gadget73]

The last used compressor I got had a bad bearing in the clutch. Had that replaced, and when we tried to charge it I found out the front seal was also shot. I spent more between buying the used compressor and having it fixed only to find out it was useless than I did buying a brand new compressor. That was on my S10 though, slightly different machine.

My Ford compressor cost me like 100 bucks on ebay. Shop around, you may get lucky. The compressor it replaced was a used OEM one that sounded like a dying meat grinder. it made cold air, but it sounded *horrible*.

[86VickyLX]

The last used compressor I got had a bad bearing in the clutch. Had that replaced, and when we tried to charge it I found out the front seal was also shot. I spent more between buying the used compressor and having it fixed only to find out it was useless than I did buying a brand new compressor. That was on my S10 though, slightly different machine.

My Ford compressor cost me like 100 bucks on ebay. Shop around, you may get lucky. The compressor it replaced was a used OEM one that sounded like a dying meat grinder. it made cold air, but it sounded *horrible*.

Sounds like mine.

[1987cp]

Anyone ever tried to put in one of those new Sandens like Vintage Air sells that are supposed to be all efficient and stuff?

[gadget73]

probably would be an upgrade. the FS6 just isn't that spectacular. Its just a matter of working out plumbing and bracketry. the stock stuff just fits, which is always handy. Something like a Sanden retrofit would probably make a lot more sense if one was doing totally different front accessories for whatever reason, which in itself isn't really that terrible of an idea. The stock accessory setup with its lack of a spring loaded tensioner and the 2 belts and all that stuff could be ditched for something better. Still gets back to being hard to justify for a stock engine. If it was future-proofing to allow a supercharger or whatever though, that would be nice.

[GM_Guy]

If it has gradually gotten warmer you might be lucky enough to just need a recharge (typical slow leaks you can't do anything about). Noticed on mine it started as a noticable engine rpm change as the compressor cycled, that was the beginning sign of a low a/c charge in hindsight. I finally got around to recharging it when it didn't cool very well any more and we're back to freezing my digits off and there is no more engine rpm variance as the compressor kicks on and off.

Alex.

[Stealthlead]

Okay well good news, my friend took a look at it. My compressor is still in good condition, the reason my idle is being effected is because there is no charge in the system at all; he said the system is attempting to do its job and suck charge but it cannot thus hurting idle. He showed me the bubble test on my visible A/C system and found a few minor cracks. He came to the conclusion it was the line near my pressure switch, and the high/low lines near the condenser that caused the freon to leak out. What I need is new o-rings for the high/low valves, new pressure switch, accumulator, recharge kit and after that it should be good to go. Will post back!