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What does this gizmo do?

chris142 on Tue June 09, 2009 9:00 PM User is offline

Year: 1993
Make: Peterbilt
Model: 379
Refrigerant Type: R134a
Country of Origin: United States

I sure do seem to get a lot of big trucks at the shop where I work.

Monday we had a 1993 Pete come in. After repairing the condensor I found a 2nd leak under the bunk. Right at the rear evaporator is an electric solonoid controlled valve thing. I'm thinking that it shuts off the flow to the rear unit when the rear is not being used. Unfortunatly I didn't take any pics.

I'm wondering why they use that. Suburbans and what not that have a rear unit don't use one so why put one in the big trucks?

TRB on Wed June 10, 2009 3:19 PM User is offlineView users profile

I believe it will be an electric expansion valve. Post the image and we can see what you're working with!


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chris142 on Wed June 10, 2009 10:49 PM User is offline

No the truck uses a regular block type expansion valve after the solonoid thing. Next time I see one I'll try to remember to snap a pic.

mk378 on Thu June 11, 2009 10:29 AM User is offline

Is the front also a TXV on those trucks? That may be the difference. When they hang a rear evaporator onto a CCOT system on the light trucks, the rear TXV will just close down completely with the rear fan off after the evaporator gets cold. The CCOT system keeps the low side from going too low where the evaporator could freeze up.

I could see a system with dual TXVs being hard to control to prevent freeze-up without having solenoid valves to cut off the refrigerant entirely to the evaporator.

chris142 on Thu June 11, 2009 8:43 PM User is offline

Some trucks use 2 Expansion valves and others use a red orifice tube in the front and a exp valve in the rear. All of em have the solonoid thing.

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