1992 MTX Air Con Issue

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SHOme1289

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As per the request of mods, I am breaking up my introduction post's list of issues into individual threads so that it is easier to have the issues addressed.

The AC compressor seems to be dragging real hard sometimes...it sometimes cycles on and off in quick 2 second intervals, and when it does, it drags the RPMS down noticeably and the belt squeaks. But it acts fine, cools very well, and cycles normally and smoothly without any odd symptoms sometimes too, while driving and/or idling, so it seems sort of random, maybe happens more frequently when it is very hot/running a long time (car was converted to R134a within the last 5 years IIRC).

The PO says the belt actually pops off and for me to avoid using it till its addressed. Over charged? Under charged? Worn compressor? Before I tear into that rats nest of stuff, having an idea of typical issues similar to this issue would be helpful to know about ahead of time. I have yet to experience the belt popping off, but when it begins acting up, you definitely know it. Any feedback would be greatly appreciated.
 

zoomlater

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here are some previous post you can read through. Did the owner say if he ever replaced the compressor or is it the original. I had a previous 92 where the owner just removed the ac pulley and bypass the compressor




 

Irish Pride

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If the belt will actually come off then my first thought is that the belt is stretched / too long or that the tensioner needs to be tightened. The belt should be tight enough so that you cannot get it off at all. Feel for play in the belt and try to adjust the tensioner. If it is really tight already then remove the belt and check for bearing wear in the compressor pulley.

-Chad
 

SHOme1289

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Ok, these are good suggestions and places to start. The puzzling thing to me is, like, right now for example, it idled in my driveway running AC on MAX for 15 minutes no issue and then driving it up and down the road in 100 degree heat exhibited no symptoms either, besides the typical loss of a bit of power from the compressor cycling (like most cars) so since it's something intermittent, and seemingly random, I'll probably start by checking the pulley bearing and clutch situation on the compressor because while it may have been behaving good just now, it does make a bit of extra odd noises at idle, plus there's definitely some serious "supercharger" sounding whine constantly coming from at least one of the pulleys bearings...I'd be ecstatic if it was just the 1 pulley responsible for all these issues. I'll have to get dirty and check it out. Also might not hurt to check the r134 charge numbers on a gauge and see what's happening there too.
 

NoSlo

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There's various metrics for measuring the AC charge, but the basic one for R134a is the static system pressure, without the car running, which should be checked with the car absolutely cold and after sitting overnight, and best with infrared thermometer gun to measure the temperature of the radiator, pump and other AC components to average out where they've settled. Best would be in a garage with stable temperature, if not cooler than room temperature to keep the pressure measured on the low end of a low side gauge. Then it is as simple as measuring the tire pressure, but with a gauge on a bottle, see chart.

The second test is to measure the cycle time of the AC system. A warmed up car, with a brick holding it at 1500rpm, should cycle on 45 seconds, off 10 seconds or so on an 80 degree day. Immediate shutoff after a few seconds likely means a plugged orifice tube or restricted condenser core, or a low charge that is barely at the threshold to trigger the switch on the accumulator/dryer.

A "retrofit" should have been new 1994-1995 dryer and hoses, the lines and the pump completely flushed of old oil, vacuumed down after system completely clean and new green o-rings installed everywhere, and finally charged correctly. A mixture of old oils or a half-ass job can be oil sludge or air in the system or way too much oil.
 

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SHOme1289

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Thanks for that information, I still haven't had the time yet between side jobs (2018 civic manual transmissions are absolute trash, what happened to Honda sticks? Jeez!) to get to far into the investigative work on the AC but today, for example, it idled perfectly with AC with minimal or very unnoticeable compressor cycles on and off, and while driving, it was working pretty good at cooling air, however still creating a noticeable drag on the engine...there was no belt squeal or issues with that, but if I noticed even the slightest of odd behavior, I shut the system off and opened the windows. It's was to frigging hot out here in Austin TX to have AC issues. It's unreal, and that's coming from someone who's all blacked-out 2012 mazda3 daily driver for the last 3 years hasn't had AC. I MUST get this sorted so it runs dependably. Thanks for the feedback so far, everyone
 

luigisho

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I would not recommend any car this old as a daily. At least without a backup. Hard to find parts, old wiring. This can be a tough road to navigate over time.
 

SHOme1289

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I hear that, I have a few other cars to fall back on, my intention is to essentially daily this one though, it's pretty low mileage and is rather solid, not afraid to put the miles on it.

As far as parts are concerned, if it ever gets really serious and I'm desperate for something, I will source another SHO entirely or make use of my keen ability to McGyver things. I also have about a half dozen salvage yards to pick from, usually stocking a minimum of a dozen or 2 old Taurii amongst them all.
 
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