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2000 Eldorado ETC A/C problem

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Getting the "Low refrig / ac off" message on the DIC, figured it needed a little top off on the charge, Low/high sides reading 100 psi while off, reading 40 low and 125 high while running. Had to jump the low pressure switch to get compressor to engage. Adding more R134 did nothing, pressures remained the same and still throwing same code. Replaced low pressure switch to no avail. No leaks detected anywhere but when I took a peak inside the blower/evaporator housing it appears the evaporator is really clogged up, looks like a home ac unit that has been run for years without a filter installed, lots of gunk. Could this be my problem? Could it be preventing the transformation of the liquid to a vapor? A/C works good while low pressure switch is jumped, gets cold and makes no noise, 44 degrees at the vents. High side pressure just seems very low.

How hard is it to remove and replace the evaporator and the heater core on these things? do they come out through the dash or from the firewall? Recently bought the car and dont have a manual for it yet.

Thanks

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I believe you need to clear the code before the AC will work without a jumper on the low pressuere switch. See this link. http://myweb.accessus.net/~090/dtcobd1.html. If not sure just disconnect the battery for a minute and the code will clear.

Also I didn't see this indicated in your post but the following is needed to check for a full charge

Clear the code

Set the temp control to Max Cold

Have some someone in the car raise the rpm to 2000 and hold it steady while you are filling and checking the pressure.

If you have no other issues with the system you shold be good !

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I believe you need to clear the code before the AC will work without a jumper on the low pressuere switch. See this link. http://myweb.accessus.net/~090/dtcobd1.html. If not sure just disconnect the battery for a minute and the code will clear.

Also I didn't see this indicated in your post but the following is needed to check for a full charge

Clear the code

Set the temp control to Max Cold

Have some someone in the car raise the rpm to 2000 and hold it steady while you are filling and checking the pressure.

If you have no other issues with the system you shold be good !

I have cleared the codes each time I try something different, I did a lot of research prior to making this post as I know how frustrating it is when people ask the same ole questions.

With the codes cleared and the low pressure sensor jumped it cools great but even at rpms up to 2000 the high pressure side never gets above 125. The compressor appears to be aftermarket and looks pretty new, although they might not have did things correctly and it could have fouled already.

I recently bought this vehicle and the ac worked great for a week then the codes came, coincidence I'm sure. I am baffled by this problem as it just doesnt make sense.

Thanks for any help. Has anybody replaced the evaporator or heater core on one of these??? I would like to talk to you.

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You need to clear the low refrigerant code and then get a can hooked up, burp the air from the charging hose, then start the car and turn on the AC. The system will pull in the refrigerant before the low refrigerant code sets.

I'm not sure what sensor you're jumpering but I do not recommend jumpering the sensors. All sorts of strange failures can result. The system uses thermistors to monitor the high and low side refrigerant temperatures and the ACM controls the compressor cycling.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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You need to clear the low refrigerant code and then get a can hooked up, burp the air from the charging hose, then start the car and turn on the AC. The system will pull in the refrigerant before the low refrigerant code sets.

I'm not sure what sensor you're jumpering but I do not recommend jumpering the sensors. All sorts of strange failures can result. The system uses thermistors to monitor the high and low side refrigerant temperatures and the ACM controls the compressor cycling.

I have cleared the codes. The system has no problem pulling in a can of R134, sucks it in within a couple minutes. The high side pressure never increases above 125 and when hooked back up the system throws the code again and I am back where I started.

This morning I turned on the heater and got a "service a/c system" message.

I never take my cars to mechanics, but I might have to let someone look at this problem.

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The high side pressure never increases above 125

Kevin, does that sounds like a clogged orifice tube?

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The high side pressure never increases above 125

Kevin, does that sounds like a clogged orifice tube?

This is what I was thinking also but, wouldn't a clog after the high pressure port cause an increase in pressure? I havn't broken into the system yet, because if this is an easy fix then why expose it to the atmosphere. If I have to replace a part then I will do the orifice tube and accumulator and O rings etc.

I am a good mechanic but will admit to not doing much with A/C systems. Although they seem pretty straight forward. Never owned a Caddy before and I am seeing things are done differently in some areas. I'm coming from the LSX platform of engines.

Thanks for the help

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A severely clogged orifice tube will tend to spike the high side and send the low side to almost 0 psi or even into a vacuum. Frost will form immediately after the restriction. Are there any other codes stored other than the low refrigerant code? It could be a failed compressor - that would explain the high side never going above 125 psi. but I need the low pressure reading in order to figure out what may be hapening.

Edited by KHE

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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A severely clogged orifice tube will tend to spike the high side and send the low side into a vacuum. Are there any other codes stored other than the low refrigerant code? It could be a failed compressor - that would explain the high side never going above 125 psi. I'd also have a look at the orifice tube at that point as it may be filled with debris from the compressor. Be sure to install the orifice tube in the proper direction or you'll destroy the low side temperature sensor.

What does the low side pressure read while the high side is at 125 psi? That will provide a clue to what's going on.

No other codes pertaining to the ac system. Low pressure side reads normal at about 45 dipping to 25 when rpms increase and then the compressor kicks back in. With the sensor jumped the system woks great and the ac vents have 44 degree air blowing out of them, when plugged back in the code throws. Compressor looks aftermarket (Arctic Air) and no oil leaks around it. Maybe it is going out, maybe they didn't replace the accumulator & condensor when they installed it, who knows whats been done before. Maybe I will just rebuild the system.

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It sounds like the system is low on freon. Going from Idle to 2000 RPM the low pressure should not drop off 20 PSI What is the outside temperature? Pressures and temp at the vents are dependant on outside temperature and relative humidty. I've tried to attach the chart for this but have not been successful.

Try this link. http://www.ackits.com/aacf/ptchart.cfm

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A severely clogged orifice tube will tend to spike the high side and send the low side to almost 0 psi or even into a vacuum. Frost will form immediately after the restriction. Are there any other codes stored other than the low refrigerant code? It could be a failed compressor - that would explain the high side never going above 125 psi. but I need the low pressure reading in order to figure out what may be hapening.

I was afraid I might have had that bass ackwards.

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Are you sure the system wasn't empty before you started adding refrigerant? If it was empty, there is air and moisture in the system. I would have the system checked for leaks as it sounds as if there is a large leak in the system. If the system is not leaking, then have it evacuated and recharged with the correct amount of refrigerant, then take the pressure readings.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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