Hi All -

I'm looking for some confirmation before I buy a new a/c compressor because the clutch on my current one won't engage.

First, I'm relatively new to this forum and have found some wonderful (and cost saving) information here. So, my thanks to all of you and the input you've had on my experience so far. I'm "shade tree mechanic" and can pretty much find my way around most any type of car. But I'd like to get some input on this one.

I have an '03 S-Type V8 (non-supercharged). When I purchased the car the a/c wasn't working and I put a cheap gauge on the LP quick connect. It read WAY OVER CHARGED. I brought it down to about 60psi with no results (I didn't really expect any to be honest).

I then came here and did some research. Based on that research...
1. I checked the relay and fuse in my front power distribution center
2. For good measure replaced the low pressure switch
3. Jumped the relay to engage the clutch (I was getting more desperate) with no results
4. I evacuated and pressurized the system and attempted a recharge. It took about half a can (65 psi) and that was it but still no clutch engagement.

Before I run out and buy a compressor is there anything else that I should check? While I love spending money on tools I don't want to spend money on parts that aren't broken.

Thanks for the help!

 

You most likely have a blocked TX or Dryer, in any case these should always be replaced after evacuating a system.

First thing to do is replace the TX valve and dryer. These are quite cheep but the TX can be a pain to install

Next test the compressor. Remove the hoses and Jumper the clutch. Start the engine and check one port has air pressure. It will a quite high 200+psi if the compressor is working.

Next connect a set of AC gauges to the high and low ports. These can be purchased very cheaply.
Next you need to hookup to a vac pump and open the high/low ports

Run the vac pump for 30-45 mins and check the gauges, you should read close to 30. If you cant vac down the system you have a major leak to repair

Assuming you now have a vacume, close the high/low ports and turn off the vac unit. Let it sit for another hour or so and see if you loose vac.

If you dont you dont have any leaks. If you do start looking with a UV lamp for the die leaks and replace the o rings. IF you cant find any you may need to add a small charge and some die to locate the leak.

If all is OK charge the system
Open start the engine, ac on full.
Open the low port and start charging up to the correct amount of refrigerant by weight
As the charge builds the system will begin to cycle.

Be careful not to overcharge the system.

The system should now be working unless you missed a step

Cheers
34by151

 

Thanks for the input/directions..they're greatly appreciated. Just a couple of quick follow-up questions before I start.

Is the "TX" valve you are referring to the expansion valve?
In the step where I test the compressor you mention removing "the hoses and Jumper the clutch". Which hoses are you referring? If these are the lines to the compressor how do I test the pressure with my manifold gauge set?

When I evacuated the system the first time I had my vacuum hooked up and it read 30 for 45 minutes. I disconnected the vacuum and the vacuum remained for about another 45 minutes. So I know I don't have a leak as of right now.

 

Yes

Remove both of the pressure lines from the compressor and run the compressor. It should be pumping air at over 200 psi

I used an extra AC compressor on my 4x4 with a truck brake tank as an air compressor to run air tools


Cheers
34by151