'95 Eagle Vision Air Conditioning

Can anyone point me at resources for troublshooting the air conditioning in my '95 Eagle Vision?

A copy of troubleshooting pages from a manual would be helpful ( I don't presently have a manual ) .

The compressor isn't cycling on, and I need to know what the circuit that controls it looks like so I can check to see whether I've got broken wires, or a sensor that's not operating properly.

I'm thinking it's probably something electrical/control related, because when I had problems with my '94 Voyager leaking, even when it was empty and I needed to add R134a, the compressor would cycle on so that I could begin the process of adding refrigerant.

Reply to
Bruce Baxter
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Reply to
Mike Walsh

The compressor clutch is activated via the compressor clutch relay in the power distribution box in the engine bay at the driver's side fender. This relay is in turn picked based on input from the A/C pressure transducer located at the bottom passenger side of the condenser, evaporator temperature sensor, and pushbutton or automatic temperature setting.

If the pressure is too low, then the relay will not activate. The relay also will not activate or will not de-activate if the evaporator temp sensor is flaky. This is the problem in my case. I bypassed all this and connected a dash switch to directly activate the relay. Downside is that I have to cycle manually to de-ice the evaporator.

In your case, first check that there is enough pressure in the system. If yes, check the pressure transducer and see if it conducts.

Reply to
Mr. Elbe

First your assumption is flawed. All modern A/C systems have a low pressure switch that cuts the compressor off if their is not sufficient pressure in the system. Many times if the system is very low the compressor will cycle on and off quickly but a flat empty system will not.

Locate the low pressure switch on yours and jump it with a wire lead or paperclip. Usually they are somewhere around or on the accumulator but I am not familiar with your particular car so I can't give you an exact location. Once you jump the switch the compressor should come on. Don't run it that way for long if it works or you will ruin your compressor!

If the compressor still doesn't come on you will need to check for 12v and trace it back through the system to find the problem. If it does come on you are going to need to find the source of the leak and repair it, replace the dryer and have the system evacuated/recharged.

Steve B.

Reply to
Steve B.

Thanks for the direction. I'll let you know how I make out once I track down my multimeter.

I love the >>

Reply to
Bruce Baxter

When I did connect a can of refrigerant (with dye and sealer, so that it can be tested), two things happened:

- I discovered my charging hose had a leak, so I'll have to get another one.

- the compressor didn't cycle on.

So I'll have to pursue the electrical avenue, and get a new charg>

refrigerant has leaked out. When you add a small about of refrigerant to the low pressure side the pressure will increase enough for the compressor to come on.

Reply to
Bruce Baxter

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Reply to
Z.Z.

refrigerant has leaked out. When you add a small about of refrigerant to the low pressure side the pressure will increase enough for the compressor to come on.

Reply to
mic canic

The first thing I'd do is put a pressure guage on it. If this car hasn't had an AC evaporator replaced, then its probably lost all its R-134a. The early LH cars had a lot of trouble with corroding the evaporator coil due to the materials changes needed for R-134a.

The AC will NOT turn on until there is some minimum pressure in the system. When charging the system with refrigerant, the vapor pressure of the R-134a in the charging system pushes enough into the system to allow the compressor to kick on and complete the charging process.

Reply to
Steve

The first level of diagnosis is complete.

I picked up a pressure guage at Walmart and checked the low side pressure. That's OK at a little over 60 PSI. I followed all the hoses around looking for a pressure switch on the low side of the system and didn't find any. The low side hose went from the manifold on top of the compressor to the H-Block. The other side of the H-Block ran to the condensor. The only pressure switch I saw was on the line going from the high side of the compressor, so I'm presuming that would be to keep the system from overpressurizing and turn the compressor off.

Is there any other pressure switch >>

Reply to
Bruce Baxter

I'm quite well acquainted with the evaporator core issue. However, I'm pretty sure the previous owner (my neighbor) told me they had already done that replacement early on. I asked specifically because I know of the issues with the lousy brittle design. I replaced one myself in the '94 Voyager we had; it was only four years old! Penny wise and pound foolish engineers and penny pinchers!

I did put a pressure guage on it today, and the low side reads about

60 PSI, whcih should be more than adequate.

I'm trying to figure out what the problem could be. What are the potential trouble points?

- leaks -- not likely in this case since we've got pressure

- electrical - a possibility, but I don't have a diagram to help me diagnose things. I had recurring issues with the A/C wiring in a VW I had because the bulk of the wires got routed near the battery and corroded.

- sensors - high pressure - this is one I don't think I want to bypass, so I'll have to have someone check the pressure. How does this sensor report high pressure? Open or closed? - low pressure - is there a sensor? Where is is located if there is one. - evap temp - I'm presuming this is going to want to shut things down if the evap ices up - are there any others?

- blocked H-Block - How to diagnose this? Wouldn't this result in excessive pressure in the high side of the circuit? I presume the sensor on the high pressure line from the compressor to the condensor would show high pressure and shut things down. I'm thinking this is the most likely thing.

What next?

- get someone to put a guage on the high side

- check the high pressure switch

- locate a low pressure switch if there is >Bruce Baxter wrote:

Reply to
Bruce Baxter

Reply to
Steve

Go over to

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and ask your questions there. The guys there are quite knowledgeable and helpful. It's a great source of A/C info.

Reply to
ZZ

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