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A/C Dash, Found problem

August 17, 2011, 02:55:20 pm

Felt the cool air from the dash was not up to snuff, was making 64f at the duct. 
So  I installed the gauges for the R-134A, found the lo press was running 37 psi and the hi press was running 435 psi.
Found the condenser fan not working.  After checking the circuit breaker, Bosch relay, finding good 12VDC to fan, no fan.
So ordered new fan from FOT, it arrived and I installed it.  Had to change the electric plug to match the existing harness, simple using two butt crimp connectors, installed the old plug to the new fan.
Anyway, now the duct temp is reading 47f.  Today the OAT is 84f.
Now the lo is 45 psi and the hi at 250 psi.
So I feel like I have won that one.  Feels good too.

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Re: A/C Dash, Found problem

Reply #1 – August 17, 2011, 11:34:23 pm

Dave, so I guess you have both a low and high connection to check pressures, I only have one on the low side. I was told by Jay at FT that they did not use the high on our years !!! I have 0 pressure on low so I guess its empty of 134a. (mind you I have not got the comp engaging as I was told it will not unless there is 134a) is does jump in if I bypass with 12v
John

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Re: A/C Dash, Found problem

Reply #2 – August 18, 2011, 06:11:40 am

John,
The compressor clutch will not pull in until there is a certain amount of pressure in the system.  You will have pressure if there is any R134A in the system, my guess would be the system is empty, and needs vacuumed before just throwing more RF134A into it.  Never saw a system with only a low side pressure port.  Would make it hard for me to figure the high side info.
On my 01 with the ISM, the ports are right at the compressor and easy to get to.
In my case with the very high pressure of 435 and the low at 37, if only had the low side to measure, it would look like more R134A was needed, but with the high side being so far out of range, it simply indicated the condenser issue, either full of dirt or no air flow as if no fan. Mine was no fan, simple for this dummy.

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Re: A/C Dash, Found problem

Reply #3 – August 18, 2011, 11:16:59 am

Dave has it right with above. The pressure switch won't allow the compressor to come on because the R134 also has compressor/system lubricant in it. Lots of installations are easy with both ports close together but some you may have to look for. The plastic cap may be missing so a little harder to find.

If system is empty, suck vacuum with Harbor Freight's air vacuum device (on sale at $15) or a real vacuum pump at about $100. You can take the receiver/dryer off and stick it in the oven overnight at 200 degrees or so and that will get rid of the moisture or new ones are cheap. Do a search online for tips, etc., if you are a DIYer. Lots of diagrams online showing all the parts, where they are and what they do.

You will need at least one can of R134 with the
 lubricant in it. Also, they make some with a leak detector dye. Get advise from Autozone, etc.

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Re: A/C Dash, Found problem

Reply #4 – August 19, 2011, 12:37:11 am

I know what the "valves" look like and have not found a high one so that was why I e-mailed Jay at FT and he told me there is only a low pressure one. The high side on or about the compressor has a blanked (sealed)  tee so it does not look like there ever was a valve there. Jay also told me it will take around 5 to 5 1/2 lbs of 134a to fill system. I have decided to leave it till I get to Sayulita as our AC guy there has said he will fix it for me and his price is good. He did my car and about 3 other RVs last winter in our park for a fraction of the cost of at home--no big deal. His company is called Mr Frosty and he speaks perfect English. Hard working young guy and nice to give him a job.

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