Charging A/C bypass relay?

[KHE]

I don't recall the point at which the high pressure cutout switch will disable the compressor but 350psi is probably pretty close. The pressures indicate an overcharge situation but if you only put in 2 lbs into the vacuumed system, something else is going on.

[Ranger]

I believe it is 430 psi Kevin. Just read that somewhere, but can't recall where.

[WarrenJ]

From Post #15:

[Tampa caddy 1998]

I went to the dealer after I found out the orifice tube Discount sold me was incorrect. The pressures are normal, last test 36/200 cold, hot higher but in range. The system has 2Lbs and works when the compressor stays on, at idle it does stay on for 20 sec or more then off for 5 or five seconds, cycles alot more at higher RPM. I placed a meter on the compressor leads and the power is being removed by the computer even at normal pressure ranges. It has a new low pressure temp switch and accumulator.

Is a sensor shutting this off I have no DTC codes. Temp goes no lower then 75 and up to 80 when on the road to to the compressor going on and off!

[KHE]

Have you checked the compressor clutch gap? That may be the issue - it should be .020-.030". If it is too wide, the clutch coil won't have enough force to pull in the clutch. Just a thought.

[Tampa caddy 1998]

No, but I could, that would not explain the voltage being removed from the compressor.

[Tampa caddy 1998]

I just bypassed the relay 38/220 and 60 Degress it works great so what is causing the compressor to cycle?

The only thing left is the following or the controller:

Ambient Air Temp Sensor

Outside Air Temp Sensor

High Side Temp Sensor

Evaporator Inlet Temp Sensor

Car Temperature Sensor

Sunload

Is there a way to test each sensor no codes show!

[KHE]

If the clutch air gap is too wide, the clutch coil will not have enough magnetic force to keep the clutch pulled in and the clutch will disengage. The gap should be .020-.030". If it is out of specification (most likely it will be too wide), you'll need a clutch plate installer tool to set it to the correct gap.

[Tampa caddy 1998]

I agree but this is not a mechancial issue; the power is clearly being removed from the clutch.

[Tampa caddy 1998]

I got it to run correctly pressures are good but the compressor keeps cycling at idle it goes to 75 Degrees; on the road 80 Degrees due to the cycling.

I just bypassed the relay 38/220 and 60 Degrees it works great so what is causing the compressor to cycle?

I placed a meter on the 12v lead on the compressor and it is going off by the controller so there is no clutch issue.

The only thing left is the following:

Controller:

New Test Readings:

Cabin Air Temp Sensor

1.629 K Ohms K ohms 2.5 Volts Running

Outside Air Temp Sensor

0.765 K ohms 1.6 power on 1.5 Volts Running

High Side Temp Sensor

1.336 K ohms 4.6 power on 4.7 Volts Running * issue?

Low side Temp Sensor

2.847 K ohms 3.2 power on 2.5 Volts Running

Low Pressure Sensor

27.7 Ohms 13.5 Volts

High Pressure Sensor

28.5 Ohms 13.5 Volts

They are 5V sensors 0 at short 5v at overload or something like that, what is the average voltage I can measure the Heater and programmer inputs:

Low pressure D-14

High Pressure D-15

Low Temp C-6

High Temp C-5

Ambient C-8 Shows correct temp for outside on display

Inside Temp D-9

Sunload says do not measure

It says the Pcm controls the relay control by providing a ground for the via the clutch relay control.

[BodybyFisher]

If you have a manual, there are diagnostic trees for the high and low side temp sensor circuits. If you do not have a manual, let us know. I have it from an 96 and 94. I was in the manual looking for the high and low side resistance readings to help you and found the trees.

The problem with testing a thermister is that its resistance at a specific temp, so its difficult to benchmark it unless they provided resistance at say 70 degrees, 100 degrees and say 150 degrees and others. I would look at those trees because it leads to 'replace sensor', "replace acp"..etc..

Mike

[Tampa caddy 1998]

I have a CD manual that is bad at best if you have the trees that would be great!

I understand the Temp/Resistance change the only thing that caught my eye was the:

High Temp switch that stayed at 4.6V cold and 4.7V running 1.33K Ohms

Ambient sensor was 1.6-1.5 V and a load of 0.756 Ohms; lower then most other sensors although the dash has the correct temp displayed.

[BodybyFisher]

Ill scan some info later and post it for you

[Tampa caddy 1998]

Thanks BBF!

I spoke to my friend at the GM dealer and he said caddy is the only one that has all thes sensors for the air. I picked up a low pressure Temp sensor the sensor I replaced was a low pressure switch. My mistake, Discount auto gave me that one. I pulled the LP Temp and found it gray and coated due to the tube being blocked. I did a vac last night and a charge will let you know. I did a ride with a meter hooked to the LP Temp Sensor and at .900 Volts compessor was on when it went to .001-000 Volts and compressor went off, so I am going down this road.

[Ranger]

Thanks BBF!

I spoke to my friend at the GM dealer and he said caddy is the only one that has all thes sensors for the air. I picked up a low pressure Temp sensor the sensor I replaced was a low pressure switch. My mistake, Discount auto gave me that one. I pulled the LP Temp and found it gray and coated due to the tube being blocked. I did a vac last night and a charge will let you know. I did a ride with a meter hooked to the LP Temp Sensor and at .900 Volts compessor was on when it went to .001-000 Volts and compressor went off, so I am going down this road.

You might want to pull the orifice tube and see what it looks like. If it is full of debris, the compressor is going and you'll need to replace the compressor, accumulator and condenser and flush all the remaining lines or you'll be in for another repair shortly.

[BodybyFisher]

I didnt get a chance to post those scans, will do it tomorrow

[Tampa caddy 1998]

Update: I replaced the Low Pressure Temp Sensor the tube is new and now I have the system working. The air went to 58 Degrees and is working great.

History:

Air warm, replaced orifice tube with a discount Auto replacment.

Pressure went up tp 370 on the high side.

Purchased correct Tube for "98-99 Deville",only; from dealer replaced pressure was good but compressor keeps cycling air not lower then 75 at idle 80 when driving.

Replaced the low pressure Temp Sensor did the Vac down and 2Lb recharge and it is now working great.

Seems like if the orifice tube has a blockage it may cause a sensor issue also, so replace both.

.

[KHE]

Glad to hear you got it running. That is the first time I have heard of the low side temp sensor causing such an issue.