Replace A/C Expansion Valve '99 GLE

Remove the evap assembly and disassemble. Also replace the drier while doing this repair.

I just removed the evaporator assembly. Here's how I did it. I'll post a link to a write up with pictures in the next couple of weeks.

1. Remove glove box. There are four screws in the corners of the glove box assembly. There are also two screws that hold the latch retainer at the top of the assembly. Pull out the glove box assembly. Disconnect the two wiring harnesses.
2. Remove the horizontal metal support brace that runs across the bottom of where the glove box hangs. There are four screws.
3. Evacuate the A/C system. You could do this first. All the pressure must be relieved prior to opening the system.
4. Disconnect the high and low pressure sides in the engine compartment at the firewall. These are the connectors for the evaporator.
5. Remove the four large screws that hold the evaporator assembly to the firewall.
6. Pull out the evaporator assembly.
7. Disassemble the evaporator assembly by removing the screws and one clamp that hold the two housing sections together.
8. Remove the evaporator and the attached expansion valve from the plastic housing.
9. Carefully disconnect the three nuts that connect the expansion valve to the evaporator.
10. Find a replacement expansion valve.
11. Reassemble and re>

Jim - great write-up. A few follow-up questions:

1. What were the symptoms that led you to diagnosing the expansion valve as the problem?
2. How did you evacuate the AC system?
3. How did you make sure that when you reassembled the evaporator assembly, valve and reattached it to the high and low lines, how did you make sure there was no leak before you recharged the system?
4. Did you recharge the system yourself after you were done? (If yes, how did you do this accurately).

Cheers, Nirav

I'm still waiting for the correct expansion valve. I ordered a Visteon from partsamerica.com. Hopefully this one is the same as the one I removed. I'm not sure the expansion valve is the problem. I'm replacing it along with the compressor and the drier. My single symptom was that it blew warm. My local dealer tested the system and found no leak. Their suggestion was replacing those three items and recharging the system. At first, I ordered the wrong compressor and drier. Finally figured out the 01/99 Max has basically a 2000 A/C system. Now I have the correct compressor and drier (partsamerica.com). I also have new O rings.

I ordered some Nissan PAG oil, although I have no idea how much to pour into the compressor. The label on the inside of the hood says the oil charge should be 8.5 fluid ounces. Does my Calsonic compressor require 46 viscosity oil? No one seems to know, not even the dealer. There must be some residual oil still in the lines. I may pour three or four ounces in the new compressor. Does evacuation remove any oil?

My plan is to reassemble the system and evacuate it with an electric vacuum pump (that I don't know where I'm going to find). I understand that I should hold the vacuum at 29.5 inches of mercury for 30 minutes to several hours to ensure that moisture in the system boils away. Then I plan to put in approximately 24 ounces of R134a (1.43 plus or minus .11 lbs). My son is ASE certified and has a manifold. I'm not going to be interested in the high and low side pressure.

The compressor did not have a catastrophic failure, so I hope the evaporator and condenser are not overly contaminated.

Hopefully there's no leak. My fingers will be crossed. If all this fails, I guess I'll have to start replacing more pieces of the system.

Great write-up - thanks for the details.

Not to ask the obvious, but did you check to see if there was the right amount of refrigerant in the system? I mean if there were no leaks, you might have just been low on refrigerant. I would think that a competent AC shop could have given you a better diagnosis than "replace all the parts"... just my 2cents... I'd hate to take on all that work as a crapshoot.

Good luck with it!

Nirav

That's the first thing I tried. I put in a little refrigerant, but it still blew warm. I'm looking for a decent vacuum pump. I see there are a few on eBay. I have a feeling I will have to evacuate the system several times before I get it all working.

Jim - it takes a very specific amount of refrigerant for the AC system to work properly. IMHO, the first thing you should do is go to a local shop that specialized in AC repair and have them just evacuate/recharge the system. It should cost less than a 100 bucks, it's all automated and they'll probably double check for leaks before charging it.

Cheers, Nirav

If this system uses a suction throttle valve you better replace it as well. It causes the same symptoms.

They were used on some model maximas and Z32's as well. This valve was used along with an expansion valve. When they stick open, they produce the problem you described. I'm glad your model doesn't use this, guess they went back to electrically cycling the compressor to control the evap temp?

Jim:

With respect to the oil quantity: What the nissan service manual recommends is to measure how much oil is left in the old compressor and put the same amount in the new compressor. Since you have no leaks, you should not have lost any oil, so the rest of the oil, not in the compressor is probably in the condenser etc.

With respect to the vacuum pump. I bought a 5 cfm (probably too big) for $160 shipped to my door, It is a Robinair 15500. You would probably be ok with a 15150 (1.5 cfm) or 15300 (3cfm) pump. I bought it from Washer Specialties Co. 800-835-1010. Ask for the person in charge of internet sales. If you are anywhere near southeast FL, you can use mine.

The best two ways to charge a system are by refrigerant weight or using the sight glass (if equipped).

I think it is very unlikely that all the components you mention were defective all defective at the same time. What were the pressure readings? Temperatures of the refrigerant lines? Was the problem not related to the heater core doors stuck in the heat position? Sometimes the receiver drier gets blocked and you will have the problem you experienced, case in which you will see a temp difference between the two lines connected to the drier. If the TXV closes, the compressor readings may appear as if the compressor was defective. Most A/C service manuals have typical pressure and temperature readings for different system problems. I could scan and email you one if interested.

I have a 96 GLE and the compressor just started cycling on then switching right off again and this repeats about every 10 seconds. Some old guy at a station in tow hooked some gauges on it and said that it seemed liked the system was blocked. He said that since the dryer was cheapest we should change that and if that didn't fix problem we should replace the evaporator. Does this seem reasonable?

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AS wrote:

Mike:

It does not sound reasonable to me.

The reason for cycling on and off will most likely be, in my opinion, that the system is low in refrigerant. $30 bucks spent at the autoparts in buying the refrigerant and the charging hose should suffice to fix your problem. The charging hose comes with instructions.

To check the dryer, just feel the temperature in both pipes that get to the dryer itself. There should not be any noticeable temp. difference when touching it by hand. The system would have to run for at least a few minutes for this problem to be noticeable.

Never heard of a blocked evaporator, unless it was blocked to air circulation (not refrigerant).

What normally blocks a system would be a defective or frozen expansion valve or a clogged orifice.

Has the A/C system been worked on? Why would it block by itself?

Good luck

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