'94 AC Diverter & Comp Cycles

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- Ric Seyler
  
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posted
15 years ago

Thu, May 8, 2008 8:47 PM

Well broke out the ole girl a couple weeks ago.. Had to put in a new battery, old one wouldn't take a charge. (it was several years old)

First day on the road the AC (Auto Option Equipped) would blow out of the defrost vents, with very very little coming out of the dash vents. Seemed cool temp wide.

After driving for a while it "Seemed" to divert a little more to the dash vents... "Seemed" to.

Broke it out again today and it's not very cool at all. Checked the compressor and it would cycle, 10-15sec on and 10-15sec off.

I'm thinking a controller problem. Because to two different symptoms.

A little history.....the heater hasn't gotten warm for the last several years, even after replacing the T-stat. Sooo that also leads me to question the controller. Maybe it's just gotten worse and has developed more symptoms.. Any guesses?

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- JimH
  
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posted
15 years ago

Fri, May 9, 2008 2:22 AM

When the heater in my '93 wouldn't blow heat, it was a clogged heater core. A flush, and it was as good as new.

When the AC came out the wrong vents, that was a vacuum check valve. I went through a spell of vacuum problems. Apparently the check valves get brittle, and leak. Once they were replaced, I've had no more problems for two years.

Hope this helps...

-- Jim

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- pj
  
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posted
15 years ago

Fri, May 9, 2008 3:37 AM

Hey Ric, Vacuum switches/valves are an excellent idea. After that, and before digging too deep, check the contacts on the control head. In humid climates those tend to corrode -- more an issue in '92 and earlier but worth a look. Comp cycling could be the result of a failed electrical pressure sensor coming out of the high side of the compressor.

-- pj

- D
- Dad
  
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posted
15 years ago

Fri, May 9, 2008 2:31 PM

Interesting, quick story..

Went to South Carolina in 0° weather and snow storms this year in my van, heater worked fine going down. Coming back only the air worked, still 0° out, taped the ducts shut to keep from freezing and was able to run the back heater. Problem was that one of the vacuum operated mixing valves had stuck, the one with 6 hose connections. Valve is mounted with the piston rod vertical leaving a nice position for the pocket in the vacuum pot to collect trash/water/salt/sand and corrode the rod and seal. Cleaned out the trash and popped it loose with a long screw driver, added some lubrication and all is well in Mudville. No room to get to the valve to change it without engine removal, or more swearing than I want to do right now.