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Topic: Testing the dash air conditioning system expansion valve in a 1995 U300 (Read 645 times) previous topic - next topic

Testing the dash air conditioning system expansion valve in a 1995 U300

Anyone know if it's possible to test the expansion valve, in the dash air system, and if so what is the procedure ? Would it be OK to use a electric hair dryer on the exposed capilliary tube ?  Temp at dash air vents is only 90 degrees despite new A/C compresser / dryer / system recharge.  Does anyone have a readout of typical operating temps ( in and out) of the various components ?  I've got an IR temp gun but no pressure gauges.  Wondering what the typical temp change is across the evaporator coil ?

Thanks,

Jon
Jon Harris
1995 U300 Unihome
Cat 3176
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Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #1 –
What are your gage readings? High side and low side.
Maybe this will help
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91 GV U300 Unihome 40' Build 3811
6V92TA Detroit

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #2 –
You can't truly diagnose without a set of gauges. They are inexpensive in the big picture, so get yourself a set. I'm not sure what fittings you have (quick connect r134a or tradiational r22 screw on type). Watch gauges as you put sensing bulb in hot water, cold water, etc.

I replaced my TXV...when I pulled it off, there were pellets of desiccant in it. It was cheap, $40. I just threw one at it.
1998 U270 34'

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #3 –
A very good source of information is the forum at Automotive Air Conditioning Bulletin Board • Index page . I have received help in the past from one of their members who posts as "Nacho." Another good forum is Automotive AC Information Forum - ACKITS.COM .
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #4 –
You can loosen the fittings slightly on either side of the TXV to release a little refrigerant while the compressor is running and see if that's where the restriction is (it is) just to satisfy your curiosity. It's obviously the smallest point in the entire system so it's gonna block there first. Take your coach somewhere that has a refrigerant recycling machine and have them recover the refrigerant, clean it, and reinstall it after changing out your TXV and receiver dryer. I had all this done to my dash air conditioning this summer and it works great now... even in 119 degree Aridzona! (pant, pant)... I think I spent about $200 if I remember correctly, which was well worth it, and I think $35 of it was the TXV, which was a generic part ordered from a catalog. The dash air conditioning is a custom system built specifically for Foretravel, so you'll probably have to buy generic replacement parts for it.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #5 –
I called the shop that replaced the TXV in my dash air conditioning, AZ Welding Equipment in Page Arizona, which is an excellent shop by the way, and asked them for the part number of the TXV they ordered. They looked it up and said they think the TXV was a 207577 from the NAPA commercial truck air conditioning catalog. This part would only work if your TXV has o rings like mine does... Write this part number down and keep it ...and write down AZ Welding Equipment in Page Arizona (928) 645-9353 too cuz they're the only place that will work on your coach in that area. Ask for Abe, who loves Foretravels and two cycle Detroit Diesels :)
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #6 –
Quote from: RRadio –
I called the shop that replaced the TXV in my dash air conditioning, AZ Welding Equipment in Page Arizona, which is an excellent shop by the way, and asked them for the part number of the TXV they ordered. They looked it up and said they think the TXV was a 207577 from the NAPA commercial truck air conditioning catalog. This part would only work if your TXV has o rings like mine does... Write this part number down and keep it ...and write down AZ Welding Equipment in Page Arizona (928) 645-9353 too cuz they're the only place that will work on your coach in that area. Ask for Abe, who loves Foretravels and two cycle Detroit Diesels :)

Scott,

Thanks for the info.  Do you know what the temp reading is now coming out of your dash vents?  10 degrees cooler here in the deep south with high humidity makes a huge difference in the sweat factor!

Jerry
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Jerry and Cindy Maddux
1993 U300/36WTBI DD6v92TA
build 4271  "Miss Lou"
1995 suzuki sidekick 4x4 toad
Gulfport, Ms

"Pride of Ownership"

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #7 –
I didn't measure the temperature in actual use driving down the highway, but Abe measured it idling there at the shop and I think it was 40 degrees or something like that. He was pretty impressed. I couldn't believe how well the dash air conditioning works in extreme temperatures. (July in AZ) I was also very impressed with the condenser mounted in the nose of the coach where it has no effect on overheating the radiator in extreme temperatures. This is a well thought out system. You're gonna love the dash AC a lot no matter how hot the weather gets. The roof AC by comparison is woefully ineffective when driving in extreme heat, even if you run both of them... at least for the driver, I never have passengers.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #8 –
Is the TXV 207577 common to the mid 90's FTs?  pc
S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..
 

Re: Testing the dash air conditioning system expansion valve in a 1995 U300

Reply #9 –
see my posts that cover most of this: Need Help With Dash A/C Problem .....
and
Need Help With Dash A/C Problem .....
and
more of my posts in that thread (including some pressure/temps etc). Sorry, not going to retype here LOL

TXV controls superheat. I had to replace a stuck TXV on my brother's house unit heat pump. It has two TXV, one for cooling, other for heatpump. Heat pump would work, cooling would not. Luckily it as connected with flare fittings instead of brazed. Technically measure subcool on TXV......
1998 U270 34'