2005 4.2L, "R"

Bought the car last year, and the AC is was working. Replaced the Heater Control Valve today and still no cold air. Though it blew "cool" air for a few minutes, it wasn't AC cold, and then it went back to blowing hot air. lol. When I tried to add freon, the cannister gauge went immediately to red, not allowing anything into the system. I'm kinda stumped. Could it be the Expansion Valve is plugged, and I need a new one? If so, where is located on the 4.2L S-type?

 

Hi Mike,

Despite the claims of the "A/C Repair-in-a-Can" R134a marketers, it is not possible to properly charge an A/C system using only one gauge for the low or suction side of the system. To understand what is happening in the system, you need two gauges, one for the suction side and one for the compression side. Two gauges helps us see if the compressor is working or if there may be an obstruction in the system. It would be prudent to have a professional diagnose the system, since there are very serious risks associated with tapping into the compression side of the system.

Cheers,

Don

 

Don,
Thanks for the info on the systems, I did not know that. But yes, I actually had two shops diagnose my system. The first local shop told me they couldn't get anything into the system, and thought it was a clogged valve. Their solution was a total "ac rebuilt" to the tune of $3100. The second shop, a week later, told me Heater Control Valve and Module, to the tune of $2000. This is when I took matters into my own hands and replaced the heater control valve for $60, and tried to charge the system and found it over pressurized. I talked to a family member who is hvac certified and he suggested the expansion valve. And this is where we are at now. I'm definitely not putting $2000-3000 into this car by paying a shop. I typically work on all my own stuff so...I can turn wrenches.

 

Harbor Freight has a cheap manifold gauge set that will get you started, but this is a field where education is even more important than tools. So start studying.

You will need to know if your compressor is the newer Sanden variable displacement type with a swash plate that tilts to vary compression, as opposed to the older compressors with a clutch that engages and disengages to modulate compression. The high side pressures behave differently between the two types of compressors.

A/C system pressures are directly-dependent on ambient air temperature, so you have to understand this and have a good R134a pressure chart for reference to get you in the ballpark.

An obstructed expansion valve should not prevent adding refrigerant unless the system is already grossly overcharged, in which case the first shop should have recovered some of the excess refrigerant to reduce the system charge.

A clogged low-side Schrader valve is possible but uncommon if not rare, and is usually easily replaced by any competent shop.

It seems more likely that your compressor is inoperative, either because it has failed, or one or more of the conditions required for it to operate is not being met due to some other malfunction in the system.

By far, the best way to charge an A/C system is to recover all refrigerant, vacuum evacuate the system, then recharge it with the correct amount of refrigerant by weight.

A competent automotive A/C tech can usually diagnose a problem like yours in less than an hour.

Cheers,

Don

 

Hiya Mike,

Those refrigerant top-off kits should include 1 additional item, but it's easy to take care of this yourself. At your local hardware store, pick up a wide roll of painter's masking tape. Cut off a piece about 2 inches long. Center this piece of the gauge on the can. Press down firmly around the edges to make sure it covers the entire gauge.

The preceding instructions were industrial-strength humor to get your attention. While debating whether to get mad at me, please read the following troubleshooting guide:

https://www.jaguarforums.com/forum/s...ol-how-185002/

It's a long read, but somewhere just before you nod off, you will see my over-inflated opinion on how it's nearly impossible to determine refrigerant quantity by reading a pressure gauge. And then work through the guide step by step to properly diagnose the system. I highly doubt the expansion valve has failed, so don't panic.

I'm not sure why two different AC shops gave you different answers. Kinda hints that at least one of them is wrong.

Be sure to test your new DCCV as detailed in the guide. If you insist it must be good because it's new, I shall move into your guest room until you repent and agree to test it anyway.

Keep in mind you may have more than one active fault. If so, fix what you find and retest.

 

What are your thoughts on the second shop's diagnoses of the climate control module also being burnt out? I understand this is a common cause of AC malfunction, in addition to the heater control valve.

 

If the DCCV was/is faulty the module may need a repair.

 

On 2003+ models, this is not uncommon. First step is to test the operation of the DCCV. See post #2 in the troubleshooting guide for details. If the test passes, the DCCV and the control module are both okay.

If the test fails, do the electrical test given in that same post. If that fails, you will see a link to a more involved electrical test of the signal from the module. That same link is to an outfit that can do a cost effective repair and upgrade of your module.

 

Can you point me to the link that shows, or a shop that can do the CCM repair? I'm in grad school right now and don't have time to read the books (links) you posted, nevermind trouble shoot and repair my module.

 

Good advice given above! I think both the shops you went to failed completely. The expansion valve is a very unlikely problem in these cars. The car is pretty much assembled around the expansion valve which is mounted dead center on the firewall. Believe me you DON'T want to even attempt that repair!

Yes the RCCM can be damaged if you don't get the DCCV changed when it goes bad. Read what Karl suggested and see there is no over protection in the module so when the DCCV goes bad it usually draws excessive current which can and will with time burn a trace out on the PCB.

If the car has navigation you have a RCCM (Remote Climate Control Module). If it does not then you just have a CCM (Climate Control Module).

Take a look and read the explanations on this web site to understand what's going on. Pictures too!
CCM Repairs

I would make time to read the books/links. Education is the key as these are not common cars. So no shops have any experience with them.
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Two things. I would definitely get a gauge reading for high and low side to start with. A/C on and off. Post the values and we can get an idea. If your climate module ends up being bad i have a good used one for my 06 s type r. Thought mine was bad but ended up being something else. Third thing i just thought of. Double check a/c clutch engaged and compressor turning. I know you said very busy with other things. Try your best and we can help