[DML] Was: AC system compressor doesn't cycle, Now: AC pressure switch
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[DML] Was: AC system compressor doesn't cycle, Now: AC pressure switch

Yes, I know all about the switch, I went through the "adjust it" 
then "don't adjust it" advice on the DML back in 2001 :) I eneded up 
buying a new switch back then. 

I did an interesting (to me anyway) experiment recently. I had my 
new switch and the old original rusty one which I had no idea if it 
had been tampered with in the past. Using some bits of hose and ac 
fittings, I hooked the new switch to my pressure regulator I use for 
HVLP paint spraying. Starting at 0 psi, I slowly increased the air 
pressure until switch closed. You can hear it close, and I used a 
meter to verify. I did this a few times and consistantly the switch 
closed at 40 psi of air. It was easy then to reset the original 
switch to match.   Might be useful if anyone has a bunch of switches 
with misadjusted settings lying around. At $9, just buying a new 
switch is probably the best idea.


--- In dmcnews@xxxxxxxxxxxxxxx, "Tom" <tomciodmc@xxxx> wrote:
> From: "David Teitelbaum"
> <SNIP>You could also have a low presure
> switch way out of adjustment. The compressor MUST cycle. Try 
> it. It is the screw in between <SNIP>
> NO NO NO, Do not touch the switch!! C'mon David... If the pressure 
is too 
> high on the low side then the switch will not activate. The switch 
> control the pressure, it's the other way around. The switch should 
> the compressor when the low side pressure drops to between 29 and 
35. When 
> the pressure stays above 50 the switch will have nothing to do 
with it.
> Dirty or plugged condenser (the thing in front of the radiator) 
will cause 
> the high side pressure to rise. Plugged orifice will cause low 
side to be 
> too low and high side to be too high. Open (broken, missing) 
orifice will 
> cause the low side to read high and high side to read low.
> In this case the high side is a bit high, but without knowing what 
> outside temperature was it's difficult to say... it might be ok. 
The low 
> side is way to high. This to me would indicate a problem with the 
> or overcharged system. When there is too much refrigerant in the 
> there is just no place for the compressed freon to go. It is 
forced through 
> the orifice at high pressure and keeps the low side pressure too 
> causing the evaporator to freeze over. 36 ounces of R-12 is 
correct but that 
> applies to factory system in a D. That means that if you have 
shorter hoses, 
> smaller accumulator, bent/damaged condenser, too much oil, etc. 
then it 
> would be too much for the system.
> I would recommend charging the system with less freon. BTW, make 
sure that 
> you are really putting 36 ounces in there. Is your measuring 
system correct? 
> If you are using a scale, is it good? And the main thing is - Are 
> putting 36 ounces by weight or 36 fluid ounces?? It's suppose to 
be a weight 
> measure. Or just switch to the metric system and use 1000 grams of 
R-12 :)
> Good luck!
> Tom Niemczewski
> tomciodmc@xxxx pl -> www.deloreana.com
> VIN 6149 (in Poland!)
> Save the dream so you can live the dream...

To address comments privately to the moderating team, please address:

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews 
Yahoo! Groups Links

<*> To visit your group on the web, go to:

<*> To unsubscribe from this group, send an email to:

<*> Your use of Yahoo! Groups is subject to:

Home Back to the Home of PROJECT VIXEN

Copyright 2006 ProjectVixen.com.  All rights reserved.

Opinions expressed in posts reflect the views of their respective authors.
DMCForum Mailing List Archive  DMCNews Mailing List Archive  DMC-UK Mailing List Archive