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Uh-uh; everything's backwards
Posted by Quasi (more from Quasi) on Wed, 3 Jul 2002 12:05:07
In Reply to: VIKINGSAAB - Expansion Valve Question, Robert Kaplan, Wed, 3 Jul 2002 09:06:34
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AC has to be the most confounding thing on the planet! I just got through going round and round with mine again.
First, the bulb thing: It's supposed to connect to the top of the expansion valve "hat". When the evaporator outlet pipe (and the attached bulb) COOLS (signifying gas flow through the evaporator), the gas in the closed tube (the bulb) contracts, which pulls on the bellows in the hat, which CLOSES the valve, to restrict the flow a bit. When the evaporator outlet pipe (and the bulb)gets WARMER (signifying a lack of gas flow), the gas expands and pushes on the bellows to OPEN the valve (to let more gas flow).
The tube that goes from the evaporator outlet connection MUST go to the underside of the "hat"; this is a pressure equalizer (on some valves it's internal - on Saabs, it's external). You've got the wrong valve, Robert. In fact, I've never seen one built the way you describe yours.
Or am I the one who's leaning, and the rest of the world's straight ...???!!!
I just installed a faulty expansion valve and had to replace it. In my case, the pressure equalization capilary allowed refrigerant to flow from the underside of the "hat" to the evaporator outlet - we determined this when we noticed ice forming on that line. This was due to a failure of the packing/seal around the rod in the expansion valve. That allowed liquid from the top of the valve - the inlet to the valve - to flow into the evaporator outlet. The upshot apparently was that high pressure (rather than evaporator outlet pressure) was applied to the underside of the "hat", and that overrode the bulb and forced the valve closed all the time.
posted by 206.72.252...
Posts in this Thread:
- VIKINGSAAB - Expansion Valve Question, Robert Kaplan, Wed, 3 Jul 2002 09:06:34
- Follow up - Here is what I found., Robert Kaplan, Wed, 3 Jul 2002 23:20:12
- Oy!, Quasi, Thu, 4 Jul 2002 00:14:28
- Now I understand ..., Quasi, Wed, 3 Jul 2002 13:13:09
- Uh-uh; everything's backwards, Quasi, Wed, 3 Jul 2002 12:05:07 <-- Viewing This Message
- Re: VIKINGSAAB - Expansion Valve Question, KeithR, Wed, 3 Jul 2002 10:27:07
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