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Shawn Burns <freezer16801@yahoo<img src=/i/dc.gif border=0 width=35 height=15>> wrote:
> Ok its 93 today and my A/C is blowing warm air. I went through the Bentley "A/C troubleshooting steps" but
> they are, to put it simply, horse shit. All I could figure out is:
>
> 1. the A/C clutch engages
> 2. My model does not have a sight window to check fluid condition or I do not know where the window is.
> 3. the fresh air blower does operate at all speeds
> 4. The pressure release valve on the compressor doesn't appear to have been pushed out.
All the same symptoms as mine.
The fan switch problem is not related to the A/C problem.
My fan switch only works on 2 and 4 and it's been that way long
before the A/C's output starts to gradually get warmer.
> The manual doesn't explain how to check for pressure leaks and only tells you to take it to someone who's
> trained if you want to do anything but look at the components of the A/C system. I am too frugal for that
> and like to do things myself when I can. If anyone has any knowledge on how to work on the A/C system,
> please share your insight. This heat sucks w/o A/C and all the clothes that I have to wear at work make
> the heat relentless.
If your A/C's output has been getting warmer gradually, like maybe over
the course of a few months to a year, it's probably just refrigerant
loss due to age and not necessarily a leak. All the couplings and clamps
and O rings in the refrigerant's path virtually guarantees such loss.
My 95 (bought Nov 1994) starts doing this from the beginning of this
year.
To do it properly, buy a leak detection kit from Pep Boys etc. The kit
has a dye bottle that is injected into the "low pressure" side of the
refrigerant's path. Then you use an UV lamp thingy (included) to see
whether there are any leaks along the way. Of course, if the leak is
in/near your evaporator, which is in the dash near the famous heater
core that's a bee-atch to get to, then you wouldn't see it.
("Real" A/C shops as gas-type detectors to detect leaks. Such detectors
are theoretically more accurate & can find leaks in hidden locations.)
Once you're certain that you do not have a leak, or if you're just lazy
(like me!), buy a R134a recharge kit. The one I got (by interdynamics)
includes 14 oz. of R134a refrigerant, and a hose/coupler/gauge do-hickey.
Follow the directions: screw hose/coupler/gauge into the low pressure
A/C port. Standing by the passenger side fender, you will see the A/C's
evaporation valve on the firewall, about in front of the passenger's
knees. The low pressure port is the thicker hose coming off of the
evaporation valve. On my 1995 GTI VR6, it's the hose on the passenger
side. Pics here:
http://www.gti-vr6.net/library/ac_heat/1995_GTI_VR6_AC_valves/index.html
Screw the can tap valve into the R134a can (back the needle all the way
out first so it won't break the can's seal as you screw the valve in).
Start car and check gauge to see if refrigerant pressure is in the proper
range. If not, start recharging: screw the needle down to puncture
the can's seal, then back the needle out to start refrigerant flow.
Mine took more than 20 minutes to empty the whole can. Shake the can
periodically to promote conversion of the liquid refrigerant inside into
gas.
You should probably NOT turn the can upside down like the instruction
says, to inject refrigerant in liquid form. Doing so will result [in] blob
of liquid refrigerant going through the compressor. If such blobs are
big enough, they may fail to vaporize by the time they reach the
compressor, which can damage the compressor because the compressor is
designed to compress a gas, not liquid.
When the gauge shows the proper pressure or when the bottle is empty,
screw the can's valve back down & remove from car. My car's A/C was
blowing 90'+ air (ambient temperature was 95') before the recharge.
After the recharge, it blows a frigid 48' at peak (after about
15 minutes at speed).
To keep track of whether I have a leak, I measured the A/C'ed air
by sticking a cooking thermometer into the one of the air vents
and noted the temperature, as well as noting the ambient air
temperature, fan & recirculation & vent/floor settings etc.
This way I can periodically do the same measurement and see if
the system's performance stays the same or has degraded (which
probably means a leak).
"Chris Kramer" <mach825@cwnet<img src=/i/dc.gif border=0 width=35 height=15>>
> Servicing and troubleshooting an AC system requires some expertise and some
> fairly expensive equipment.
That depends on what the problem is and what kind of result one wants.
For example, a loss of refrigerant definitely means that there is now
some atmospheric air in the system. Such air will reduce the system's
efficiency because air (oxygen, nitrogen, carbon dioxide & monoxide,
and water) does not [have] nearly the same refrigerant qualities as R134a.
Also, moisture in that air may cause problem in the system later on.
A "real" recharge job would first include a leak detection, then
evacuating the system (capturing the old refrigerant), "flushing" the
system with nitrogen (or another relatively inert gas) to push out the
"bad" stuff like air and moisture, then recharging with refrigerant.
(In fact, I think I saw a "flush" kit at Pep Boys as well.)
So the question is, is one willing to have a half-assed solution
to one's A/C problem and not pay so much? (My recharge kit was $25-$30
or something like that.)
> It may not even be legal for a private citizen
> to open the system in some states.
True enough. If your Pep Boys has R134a kits on their shelf then I'd
think that it's legal.
Finally, Google for "car air conditioning recharging" or variants
thereof.
--
Andy Nguyen
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(GTI)