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Dash Air Thermostatic Expansion Valve - Printable Version

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Dash Air Thermostatic Expansion Valve - Richard - 02-02-2019

My dash air became inop because of a plugged thermostatic expansion valve. Classic symptoms were very low suction pressure and very high high side pressures with no cooling. Simple diagnosis but not so simple of a fix.

First challenge is to remove the old TXV. In my 99 it is in the bowels of the lower dash area. I finally gained limited access by removing both the HWH control panel and the rear view monitor. After evacuating the system, don't snigger I have a reclaim unit, I removed the TXV. The hunt was now on. No identifying info. It was made by Parker Hannifin, but they sold their automotive biz years ago. After two days of looking at expansion valve catalogs and surfing the interweb, the valve was identified. A Four Seasons 38872 is a workable replacement. You can get one here. https://www.amazon.com/gp/product/B000C2MAKO/ref=ppx_yo_dt_b_asin_title_o05__o00_s00?ie=UTF8&psc=1

I also replaced the dryer, a rather generic part, but try getting one at the local parts house without a make model and year of car. I used this one  Four Seasons 33321. https://www.amazon.com/gp/product/B000DCNENU/ref=ppx_yo_dt_b_asin_title_o06__o00_s00?ie=UTF8&psc=1

I discovered a lot of debris at the filter dryer so I decided to flush the system. Holy moly, I got about a teaspoon, no exaggeration of grit out of the system. No wonder the TXV was stopped up. I suspect the original filter drier failed in some manner. 

Pulled a vac for a couple of hours, no leak down. Pumped up with N2 and no leak down. Put in 3.5 lbs of liquid R134a on the high side without the motor running. I let that sit for an hour. Then cranked the engine, and put in about another 8 oz of vapor on the low side. Ambient temp was 75. Low side was a steady 12 psi, and high was 175 psi. The gauges had never been this steady before. Vent temperature was frosty ! Oh yeah, I did put replacement PAG oil in for what I captured on the flush. 

Total refrigerant capacity for the system was very close to 4 lbs 134a. 

So, in addition to the part numbers. The primo lesson was if you tear into the dash air system, flush it, or you may be going back for rework soon. 

I will tweak the refrigerant level if necessary when the weather gets warmer. 

Hope this helps you someday.

RE: Dash Air Thermostatic Expansion Valve - Latitude 28 - 07-30-2020

It wasn't two weeks after Richard posted his TXV replacement that our dash air quit cooling.  Been real busy on other projects and finally had time to do some troubleshooting.  I to, have a bad/plugged TXV....spoke with Richard on gaining access to the evaporator....so far so good.  But, I am having trouble figuring out how to take the ADS speaker out of the passenger side floor console....(see attached pic).  Does anyone know the secret to removing these things?
   
Thank you in advance for the help!

RE: Dash Air Thermostatic Expansion Valve - Richard - 07-30-2020

Gently remove the screen covering by using a small thin screwdriver and lifting up at any edge. The screen is rolled and just wedges into a groove. When you get the screen off you will screw the four screws that hold the plate in. Use the drill, for they are looooooong. Once those screws are removed the rest will be obvious.

RE: Dash Air Thermostatic Expansion Valve - DK on the road - 07-30-2020

I don't have the proper equipment to evacuate. I should get this and educate myself further on this.

I have paid Newell to do exactly what Richard did after the AC compressor disintegrated and loaded the line with debris. Newell lifts the whole dash about 24" and places it on sticks. It took them about and 3 hrs for the R&R of the dash and TXV. I don't remember what that task alone cost, but i'm sure we were close to a BOAT (i like that phrase, about a thousand, used elsewhere in the forum).

I need to lift the dash and replace or tighten the lines on my heater core in the same area. I wasn't looking forward to doing this on the road.

RE: Dash Air Thermostatic Expansion Valve - Latitude 28 - 07-30-2020

Richard,
Thanks for the tip....once i pried on the right seam the grill popped right off with no issues. Next subject, i am continually amazed at the dexterity and contortionism (sic) you can do in order to get to some of these "deep in the bowel" areas. I can see the TXV and put my finger on it and totally understand why Newell lifted the dash. I have got a few days waiting on parts to do some figuring out what I need to do. Thanks again!