AC Help

[MKing7]

A few weeks ago the passenger side would blow cold and drivers was warm. Eventually, at first, the drivers side would blow colder.



Now they're both warm. Grabbed a refrigerant kit at Walmart and the pressure on the low side port is way high. Over 100 psi.



I've been saying for a while that I needed to learn ac. Guess I got my wish. Thanks for any help.

 

[B.G. Smith]

The compressor has to be running to get a pressure that will indicate some conditions of the unit. If it is 100# while running the compressor may have gave up? bg

 

[MKing7]

I don't think the compressor is coming on.

 

[B.G. Smith]

Just looked at mine, there is no clutch cycling switch on the receiver/dryer. I am guessing now. I suspect the unit is low on refrigerant and the computer has locked it out to prevent compressor damage. I would take the truck to an auto parts store and get them to check for codes, if it has a code on the AC, have them reset it if possible and add at least on can of refrigerant when you turn the AC back on. Don't turn AC on until you have the refrigerant hooked up and ready to go. bg

 

[JFought]

if pressure is two low, the switch won't allow it to cycle on.

check the pressure. it typical for driversid to be warm, and passenger to be colder- a classic sign of low refer giant

 

[BHatton]

As an added note to the above posts, 06s had a problem with an internal fuse inside the compressor. This fuse is not servicable. Compressors had to be replaced. My Dodge boys could not tell me if this fuse was heat related (thermal fuse) or electrical.

B

 

[MKing7]

Well. No codes present. Compressor won't come on but light on dash does. I guess it might not mean anything but the low pressure reading is over 100psi. Tried another gauge and same thing.

 

[JJPage]

Well. No codes present. Compressor won't come on but light on dash does. I guess it might not mean anything but the low pressure reading is over 100psi. Tried another gauge and same thing.

If the system is at rest, both the low and high side equalize, so pressure sounds about normal for an equalized system. If the low side is at 100 psi while operating, you have problems, something has let loose in the compressor.



Sounds like the low pressure switch may be keeping the compressor from engaging. Connect a can of refrigerant(134a?) to the low side, turn on the AC to max, and let the refrigerant flow into the system. One can(12oz) may/may not be enough to keep the compressor engaged.



I am not sure what operating pressures are for 134a, for r22 low=60/74, high 200+ depending on load, but these were commercial applications I used to maintain.

 

[Bob4x4]

100 psi on the low side with the compressor not running... ... ... . ck to see if you have power to the compressor. . you probably do sounds like time for a compressor

 

[B.G. Smith]

MKing7, I have read of some folks having trouble with the connection at the compressor like rocks/debris hitting and damaging the connection. That would be an under the truck chore. If you do check this out the engine has to be running for the compressor to come on. Unplug the connector and check for voltage with the AC on, also check the compressor side of the circuit for continuity/resistance. I don't think this model trucks has the clutch cycling switch but uses the thermister which is mounted on the face of the evaporator to cycle the compressor. Don't have a schematic but if you could identify the wires to the thermister you could by-pass it to eliminate it as being the problem. How far West are you in Texas? Good luck. bg

 

[MKing7]

100 psi on the low side with the compressor not running... ... ... . ck to see if you have power to the compressor. . you probably do sounds like time for a compressor

That's not what I wanted to hear...

 

[MKing7]

MKing7, I have read of some folks having trouble with the connection at the compressor like rocks/debris hitting and damaging the connection. That would be an under the truck chore. If you do check this out the engine has to be running for the compressor to come on. Unplug the connector and check for voltage with the AC on, also check the compressor side of the circuit for continuity/resistance. I don't think this model trucks has the clutch cycling switch but uses the thermister which is mounted on the face of the evaporator to cycle the compressor. Don't have a schematic but if you could identify the wires to the thermister you could by-pass it to eliminate it as being the problem. How far West are you in Texas? Good luck. bg

I took a quick look a few minutes ago and there is a two wire connection (I think it was two, could be 3. . it was hard to see without a light) and it seemed like it might be frayed but probably not with my luck.



Not west Texas... West, TX.



It's about 20 miles north of Waco. It throws everyone off... .

 

[JJPage]

100 psi on the low side with the compressor not running... ... ... . ck to see if you have power to the compressor. . you probably do sounds like time for a compressor

Ok, my truck has been setting for about a month, it is around 35* outside, I did not start my truck, I just connected my gauges up to the low side, just over 90lbs pressure at rest.



There is nothing wrong with my AC, it works just fine, so why do you believe it's time for a compressor for the OP with this info?



As I stated earlier, if his suction pressure is that high while operating/compressor running, then something has happened to allow refrigerant to bypass the metering device. If his suction/low side pressure is that high at rest, depending on ambient temp, I do not see a problem as both suction and discharge pressure equalize at rest.



Am I missing something here? I have not professionally worked on automotive systems, but I have worked on and maintained commercial applications, from small splits, to package units, and centrifugal chillers up to 400 tons.



Maybe his compressor is shot, but his equalized pressure is not pointing that out.