92 164L ac truble shooting help - Alfa Romeo Bulletin Board & Forums

 
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post #1 of 8 (permalink) Old 07-07-2016, 06:22 PM Thread Starter
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92 164L ac truble shooting help

I have a 92 164L that I bought this past winter with a VERY good body but a huge list of problems, so I saved it from the crusher for $250. Before it was destined for the crusher it was parked for about 8 years in a garage! The car is currently running and driving very well so I decided to try and figure out the ac, I bought from Napa the A/C RETROFIT KIT BK 7652979 with some success. The ac system was empty when I got the car, about 1 psi was present.
Before I filled the system I evacuated it through the low pressure side with an ac compressor from an old window ac unit and pulled a pretty strong vacuum on it for 10 min or so. I took it for about a 10 mile test drive enjoying nice cool air on a 90 degree day. After the test drive the POA valve was VERY cold and condensing a lot so I assume all is well, quick easy fix.

Now with the car just sitting idling the ac pump runs for a short time then shuts off and stays off for quit awhile before starting back up, at no time is the fan behind the radiator coming on while the ac pump is running. The fan only comes on when the engine coolant gets hot enough then it comes on for little bit then shuts off.

I have not yet invested in a 4 way manifold gauge set but till then I have no ideal what pressures are going on in the high pressure side.
I can tell you the low pressure side when the pump is running is reading between 30 and 50psi depending on engine rpm. When the pump is off it rises quickly to about 80psi.

Any help in the mater is greatly appreciated, I admit I only know the basics to ac, for as far as I'm concerned its witchcraft!

Last edited by 67 Ossodiseppia; 07-07-2016 at 07:47 PM.
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post #2 of 8 (permalink) Old 07-07-2016, 09:38 PM
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I wouldn't let one of those "retrofit" kits even touch any car I own.

That said, it's impossible to even guess what is going on without a set of pressure gauges.

John Stewart
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post #3 of 8 (permalink) Old 07-08-2016, 02:48 AM
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System probably shutting off compressor because cooling fan not running and A/C high side pressure switch in trinary switch engaging to do that for safety.

You need to verify low speed cooling fan brown wiring from trinary switch back to pin 86 of low speed relay is good. With key on jumper brown and black wire at trinary switch on a/c receiver dryer and see if cooling fan comes on.

If relay clicks but fan does not work then you may also have a fan resistor problem.

Ciao, Alfisto Steve
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Daily drivers: USA models - 1991 164S Black Beauty II ALFISTO;

Daughter's current ride: BB1 my 164L and Her Granddads 2002 Ford Taurus is back up.

New parts hauler but not car hauler 2004 Jeep Grand Cherokee Overland 4.7L H.O. V-8

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post #4 of 8 (permalink) Old 07-08-2016, 09:07 AM Thread Starter
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Thanks Steve, I'm really impressed with your diagnostic skills, especially without having the car in front of you!

I cleaned up the relays and put dielectric grease on the prongs, I was getting 6 volts at pin 87, come to find out the resistor was heavily rusted, luckily I had a spare that came off the parts car and all is well! The only concern I have is the compatibility of the retrofit R134A, at some point I will do this properly and remove the pump, service the pump and change the oil and seals and use regular R134A.
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post #5 of 8 (permalink) Old 07-08-2016, 09:31 AM
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Letting the system trip the safety switch on the high side is pretty crazy, IMO . . . . knowingly or not. Physics doesn't care about intent. That switch is set to trip at 391.5 psi, which is scary high. Combine that with very old hoses in unknown condition and you've got a potential for a Darwin Award contender. I highly discourage anyone from servicing an air conditioning system without a good foundation of the basics, and basic tools like a set of pressure gauges.

If you're just trying to drive the car as cheap as possible until it craters and don't really care about the long term affects, then what you're doing makes sense with a cheapo conversion.

Hopefully the kit does ok, but worse-case is really bad if the compressor suffers the "black death." If that happens, it contaminates the entire system with tiny tiny black aluminum flakes which are near impossible to flush out and clean completely . . . especially the condenser, evaporator, and POA valve. If that happens, the work involved goes up considerably, since you might have to pull/replace the evaporator.

Also, you said that the system was almost completely down on refrigerant. There is probably still a leak and replacing the R12 with the smaller molecule R134a is just going to make it worse.

John Stewart
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Last edited by Roadtrip; 07-08-2016 at 09:41 AM.
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post #6 of 8 (permalink) Old 07-08-2016, 07:23 PM Thread Starter
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Well as of now I'm happy with a relatively cheep fix, I admit I have been meaning to get a set of gauges for some time now.

I've already rebuilt the steering rack and replaced all the power steering lines, replaced the camshafts and tappets, water pump, timing belt, the clutch master and slave cylinder, all new brakes including some hard lines, and a new fuel pump and filter. I've got plenty of spare parts if the ac totally craps out. Its been behind my machine shop up in there air since February, so right now I just want to enjoy the car.
To be honest I probably should of parted the car out along with the other one that this car came with but I just couldn't see cutting up an original paint 99% rust free car regardless of its mechanical state of disrepair.

In the near future I intend to do this properly but I have a few questions, When converting to R134A besides replacing the receiver-dryer and hoses is the only thing that needs to be done to the pump is changing the oil in it and removing as much oil from the condenser as possible? what about the seals on the pistons in the pump itself?
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post #7 of 8 (permalink) Old 07-22-2016, 07:42 AM
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Yes, you want to get as much of the old mineral oil out as possible. Internal compressor parts are not a factor. Flushing the old mineral oil out of the evaporator, and especially the condenser, is difficult. I'd highly recommend that when converting to R134 that you replace the condenser with a parallel flow one that is about 30% more efficient. They only cost about $100. The Alfa A/C isn't a stellar performer in the first place and converting to R134 from Freon isn't going to make it better. Replacing hoses isn't really necessary considering the expense. Just plan on topping the system off with a can of R134 every spring to compensate for seepage out the non-barrier R12 hoses.

The important part is that in the conversion that you use Ester oil and not PAG oil. PAG is not compatible with the residual R12 mineral oil, whereas Ester tolerates it.

Download the Conversion Guide for more specific info.

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John Stewart
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Last edited by Roadtrip; 07-22-2016 at 07:55 AM.
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post #8 of 8 (permalink) Old 08-02-2016, 06:00 AM
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I have survived working on a 1991 and a 1994 164 AC system. First, 10 minutes of vacuum isn't enough to dry a system. Use for 45-60 minutes. Secondly, if the fan isn't coming on, it could be the trinary swich which screws onto the receiver /dryer. That, by the way should be replaced after 8 idle years. The reality is you need gauges. They aren't that expensive (Harbor Freight). Then you can read the high and low sides. The early 164's tended to get overcharged because the system was'nt well engineered. That should be avoided as it will blow the compressor seals.

Doug Bruce
Atlanta
1994 164 Alfa
1972 Fiat Special
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