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Old 02-18-2010, 02:46 PM   #1
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Location: Pikeville, NC
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A/C Expansion Valve insulation

I recently had a new A/C compressor/clutch installed on my 8.1L gas, '02, W-22 chassis MountainAire. The clutch bearing was howling. A new expansion Valve also had to be installed.

When I got it home, I noticed the original, black sticky tape insulation was messed up on the new expansion valve. It is a "MUST" to have this valve insulated properly. We then left on a 5 month trip. I went on a fruitless search for this tape to local auto parts stores-- forget it! Half of them didn't even know what I was talking about. Two places told me to go to Lowes or Home Depot.

I got on the internet and located the stuff, and ordered it from these folks- Great service ! It's called "Prestite Tape".

I now have enough to redo half the RV park, plus the Russian Army.

Here are the pictures of this little job.

This is what I found when I got the rig home

Here is the new "Expansion Valve" after I cleaned all the "gook" off

Here's the roll of the "Prestite Tape". It's 2" wide.

Use a pair of sissors and trim to fit.
Press in place- Overlap where necessary. The material is easy to use. It kinda reminds me of scotch tape- It will permanently stick to anything it touches- Be careful!

Cheers and good luck if you need to do this,

Max H,
2002 Newmar Mountain Aire, 37', 3778, W-22, 8.1 Vortac, Ultra Power upgrade, CAI (cold air intake), Taylor wires, colder plugs, Koni shocks.
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Old 02-18-2010, 06:15 PM   #2
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Thanks for the pictures. I think I need to do that on my 2008 Winnie. I just need to find the expansion valve.

Can you tell me what your symptoms were when you were traveling down the highway trying to stay cool? In my case it starts blowing warm air. I can turn the AC off for 20 minutes and back on and it pushes out 48 degrees until it starts to blow warm again.


Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2008 Winnebago Destination 39W
It is what it is, and then it is what you make of it.
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Old 02-18-2010, 07:42 PM   #3
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Hi Wayne M,

I am no expert on A/C systems. You can go to the links I have highlighted below and look at the two different types of restrictor devices for the coolant.

1- The first type is the "expansion valve" which I have. It is almost always located immediately before the evaporator. It can be enclosed internally inside the evaporator housing. Mine is not- It is readily accessible under the hood of my rig.

2- The second type is the "orfice tube" which is an inline tube type restrictor. It can be located in about three different places. Look at this link.

The purpose of both of these devices is to change the high pressure liquid coolant (usuallyfreon) coming from the condenser into a low pressure liquid going into the evaporator. Any kind of debris can clog up either one of these devices, thereby rendering the A/C system inoperable. The advantage of the orfice tube type is that it has no moving parts- It kinda looks like a round piece of hose. Here is a close up of the orfice tube- it has "dimples" on it.

I had no problem with my old compressor except that the clutch bearing for the A/C compressor was starting to howl. I didn't want the bearing to seize going down the road and locking up and tearing up the serpentine belt, leaving me parked on the side of the road.

I don't know if the orfice tube type has to be insulated like the expansion valve type .

I can tell you my system is made up of parts from across the automotive sector. My new compressor is from a Chevrolet V-6 Blazer and the expansion valve is from a '98 Jeep.

The shop that did the compressor change left the expansion valve exposed as my first picture showed. I guess $780 wasn't enough money for them to install new insulating tape on this valve . This part can freeze and ice up if exposed to hot humid air (so I'm told), and the whole system will not work properly. I had to fix that.
Max H,
2002 Newmar Mountain Aire, 37', 3778, W-22, 8.1 Vortac, Ultra Power upgrade, CAI (cold air intake), Taylor wires, colder plugs, Koni shocks.
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Old 02-18-2010, 09:12 PM   #4
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wow i cant beleive how inexpensive the tape is, everyone should have a roll of it,

thanks for the find
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are 6 slides
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