Waleedjatt

How long do you think it takes to defrost?

As on a very hot morning i turn the car on almost after 7 or 8 hours and it doesnt cool, would this problem cause that aswell?

rkw77080

OK, that does not sound like a frozen-moisture problem... It should defrost within minutes after the refrigerant circulation stopped.

rkw77080

Does the A/C indicator blink when the cooling stopped? Do you have access to a OBDII scanner to see if you have any DTC (Diagnostic Trouble Code)?

Waleedjatt

No blinking light for the AC, comp starts fine as there is change in the RPM, i went out few minutes ago to check the AC, it was like cooling at the most minimal level, it was giving out freon but at a very low level.

Im really going crazy here..

Waleedjatt

I do have an OBDll but i dont know if it is able to show any codes.

rkw77080

When you say "it was giving out freon but at a very low level", how did you determine this? looking at the sight glass?

Waleedjatt

No, the cooling was at a very minimal level even on the coldest setting, im unable to see anything through the looking class its always black for some reason.

I just went and started up my car right now and AC started working until i turned it off and back on again, i did the fault code search with OBDll but nothing showed up, 0 fault codes.

However idk if its me or just the car, i did felt a sudden drop in rpm after which AC started cooling, and even on the road when im driving i feel drop in RPM specially when the AC is on, anything related to this?

Is there a relay or something which might be causing this? Fuse is fine i checked it and even replaced it with a new one. Just a hunch.

rkw77080

When the AC system demands more cooling, a signal is sent to the compressor solenoid to change the amount of compression the AC compressor must perform - this puts a heavier load on the engine, which causes the RPM to drop. If the solenoid is not functioning properly (either the solenoid is failing, or if its signal wire is damaged), the compressor will not perform the required compression to produce the desired cooling.

According to the repair manual, an open or short circuit to the solenoid will create a DTC B1451, and the AC indicator will blink. You did not observe either of these conditions.

The repair manual also says that the proper measurement for the solenoid terminals should be 10-11 ohms at 20 degC. This would be a logical place to check next - you may have a failing solenoid that is out of the 10-11 ohms range, but not open or short circuit.

Intermittent electrical problem is very difficult to troubleshoot. Since your AC operates occasionally, we can rule out a blown fuse or a bad relay. It is most likely something temperature related.

Attached is the troubleshooting procedure for the compressor solenoid circuit B1451. I was not able to locate any information on how long the DTC stays in memory, and also, most consumer OBDII scanners can only read the "P" DTC.

Waleedjatt

IF it turns out to be a failing solenoid, whats the fix for it? Change the compressor?


Just to add i have a little bit of leakage in the radiator but no overheating.

rkw77080

The solenoid is built in to the compressor. So if the solenoid is not tested to the specification, the easiest thing to do is to replace the entire compressor. Rebuilding the compressor may also be another option.

Waleedjatt

While driving back home from work, early morning at 5 AC worked fine, got slow at one point i just shut it off and turned it back on, worked like a charm all the way home.

nav66

Hi Guys - 2005 LS430 - A/C works occasionally. The sight glass check seems normal..full, no bubbles except a burst of bubbles on shutdown. I'm focusing on the pressure switch(es) first. I see one pressure switch beside the sight glass. Is that a high or low pressure switch? Are there two pressure switches?..if yes, where is there other located? Thanks - Bill

Abigail

Did you figure it out in the past 4 years? i'm having the same problem in my gs300.

Update: Replaced AC compressor, condenser, and expansion valve and now everything works fine.