[AT] OT Hydrocarbon Refrigerant

[charlie hill]

Doesn't work out so well for airships either.

Charlie

-----Original Message----- 
From: Steve W. 
Sent: Thursday, June 28, 2012 11:37 AM 
To: Antique tractor email discussion group 
Subject: Re: [AT] OT Hydrocarbon Refrigerant 

Cecil R Bearden wrote:
> OK, I know this is off topic, but if I donh't have A/C in the tractors 
> and trucks this summer, I won't be able to drive these antique tractors.
> 
> I also have heard all the arguments about  HC refrigerants being unsafe 
> and all that other crap.   I have tried to research the web about folks 
> experience with these and every time I find something relevant the 
> thread is hijacked by some all-knowing guru who keeps flaming the person 
> for using something other that what the politicians and the Dupont owned 
> EPA has dictated.   SO, Dont start with the safety etc CRAP.. I have 
> heard and read it all.
> 
> I have used Red Tek for years but it has been on capillary tube or 
> orifice tube systems.   I recently had problems with my 94 Dodge Van 
> with rear air not cooling.  It would get 70 deg, but not lower.  It used 
> to blow 40deg air on 134A.    I pumped it down and added ES-12A, the 
> same thing as Red Tek, and I would get a sweating suction line, but only 
> 68deg air in a 98deg outside temp.   gauge readings were 175 to 200 high 
> and 35 on the low.   I changed the expansion valve and drier and got the 
> same  results.   I then changed the compressor and recharged without 
> pumping down the system as was described in some notes on ES-12A 
> (Envirosafe Website)  I got about 205 -210 high side and 35 to 40 low, 
> with 100 deg outside air and working in the shade ( My outdoor shop).  
> At 205 to 210 high side, the gauge needle was fluttering or vibrating 
> madly from 195 to 215.  If I lowered the pressure by letting some 
> refrigerant out, it would quit fluttering at 195.   I did not have any 
> sweating on the suction line this time, and the air was 70 deg out the 
> vent.  I might add that the vent temp was the same front and rear.   The 
> systems are connected in parallel, so if one exp valve is bypassing, 
> then that is probably the high pressure reached.   I varied the amount 
> of refrigerant etc, but cannot get anything lower than 70 deg out the 
> vent.   I have opened the evaporator box, and made sure I have a clean 
> evaporator to get the max air flow.
> 
> I contacted Enviro safe tech who suggested that the expansion valve was 
> causing the flutter and allowing refrig to bypass at a lower pressure 
> than needed to get a full refrigerant =coverage on the evaporator.   
> Since the front and rear are connected in parallel, you cannot easily 
> determine which valve is the problem.   I replaced the front.
> 
> Any suggestions.    I used the ES-12A because the price of 134A has 
> gotten expensive.
> 
> Cecil in OKla
> 
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I'll leave the choice of gas to you. Just keep in mind that one of the 
largest proponents of using hydrocarbon in a mobile A/C system blew 
himself up at a demonstration of how safe it is.


That said:
  Is this a factory system or a conversion van? Different parts used 
depending on what the rear is.
I have worked with a few split systems on conversion vans and found that 
the rear valves tend to fail much sooner than the factory parts up 
front. Especially when they used different valve types (The last one I 
worked on had a TXV in the back but an orifice tube up front !)

If the book is correct yours should have two TXVs in the system.

I'm betting the rear unit has a corroded thermal tube. That would tell 
the valve that the interior temp of the vehicle is cold already and 
close the valve down to restrict floe in the back.

You will also want to replace the rear drier when you pull it apart.

-- 
Steve W.
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