Hi....it's 110 outside and my AC doesn't work

I have a 2004 3.0 V6 AWD X Type with 73,000 miles.

Symptoms/Situation

When the ambient temperature is 95 degrees or less:

The compressor high pressure release valve sometimes go off once within a few minutes after I start my car. The air conditioning proceeds to be nice and cold for the entire commute (this is usually on my way to work in the morning).

Sorry, I don't have pressure readings during these ambient conditions.

When the ambient temperature is above 100 (105-115) degrees

The compressor low side pressure reports 80 at idle and 65psi at 1500-2000 RPM.

The compressor high side pressure reports 350 at idle and spikes over 450-500 at 1500-200 RPM and intermittently triggers the high side pressure release valve.

The air conditioning is comfortably cool, but not cold at idle. The a/c is cooler than ambient while driving, but is unable to cool the car. We can often hear the compressor cycling on and off (hence the lack of cold air).

What we have done so far.

When I bought the car 18 months ago I didn't realize the driver side radiator fan was broken (physically). When I was under the car for a different reason, I noticed the fan was broken. When my a/c started having issues a month ago we decided the high temps (115+) could be causing the single working fan to be insufficient. (Side note, the engine temperature never climbed past the half way point).

1. As a result, I bought an aftermarket radiator fan unit, with the shroud, and replaced it a week or two ago. This resulted in two working fans, but no change in the a/c problem.

2. While we were doing the radiator fan, I also followed the TSB to reverse the compressor spring and valve. This was more precautionary since my symptoms (cold at idle, warm while driving) was the opposite of the common problem.

We had the system evacuated, vacuumed and refilled with freon after the TSB repair. The result was no change in the a/c problems.

3. So after doing some research, we thought we might have a clog in the system. We went to the parts store and bought a new orifice tube. We took the old tube out, it had two shiny flecks on it, about the size of large pepper flakes, but was otherwise pretty clean. We installed the new orifice tube and the result was no change in the a/c problems.

The system was again evacuated, vacuumed, and refilled at 1lb 12oz.

The ac pressures above, 80-60 low side and 370-500 high side are the same today after the various repairs.

It doesn't appear that the condenser is blocked/dirty. The system does not appear to be overfilled. The system holds it's vacuum pressure, and system pressures so there does not appear to be a leak. We did not see any resin in the orifice tube indicating a broken/damaged drier/desiccant bag.


So, what do we check next and does anyone have some ideas? Thanks in advance!

Jonathan

 

It sounds like an overcharge system, or there is a bunch of stuff blocking the air flow to the radiator, and condenser. You should be running a pressure in that heat of no more than 43psi on the low side. If your over pressure valve is popping off, there is probably something blocking the system somewhere.

I hate to tell you this, but have the system evacuated again, and when it is, have the hoses connected to both sides, but only open one hose for the evacuation. The pressures should equalize almost immediately, even though it may take a few seconds going through the new orafice tube. If it does not, you have a blockage somewhere.

If that is the case, and since Jag parts are so expensive, I usually put the receiver dryer in the oven at 200 degrees, to dry it out again. It is unlikely the evaporator is clogged, because those are pretty big tubes. Get a flush kit, and flush out the condenser, and all the open parts of the system you can get to, even the evaporator. Use compressed air, to blow out the fluid from flushing out the system. If you can't blow through a certain part of the system, that component will need to be replaced. If you flushed and blew out the compressor also, before the next vacuum and recharge, you will need to add the prescribed type and amount of oil to the system. DO NOT pour a lot of oil into the compressor, or it will lock up, when you put the air back on.

Take your HOT 90% dry dryer out of the oven, blow it out also, without the cleaning fluid, and install it back into the system. When you put the system back together, be sure to use NEW "O" rings, so you don't develop a leak instead of a clog. Evacuate and charge the system, and things should be Jake.

The two tiny metal particles, that you found near the orifice tube could simply be because of the pressure you were running. If there are more flecks you might need to replace the compressor.

This type of AC cleaning would probably cost you 5 hours labor, without parts, and if you need a compressor, you can add that to the labor and new parts. It is up to you, if you want to do this yourself or not. Be sure to clean in front of the condenser first though.......Take care....Mike

 

 

Thanks for the info guys, I'll see how it goes. Luckily my dad was a technician for Jaguar at their proving grounds facility out here in AZ, so he helps with a lot of these repairs and the necessary tools.

 

A very good bet is the condensor. If you saw some flecks in the orifice filter, there are probably more in the condensor.


There is a huge number of small passages in that unit, the actual diameter of each is about the size of a 4H pencil lead, and it doesn't take much to block them.


When they do get blocked, it is a double whammy; the amount of heat transfer is reduced, because part of the transfer path is lost, and the pressure rises, since the same amount of refrigerant now has less space to expand in.


The good news: the condensors are pretty inexpensive, as long as you can swing your own wrenches!

 

Is it worth trying to flush/clean out the condenser first? Or just go straight to a replacement?