96 EX V6 intermittent AC cooling.

96 EX V6 has intermittent cooling. Sometimes very cool & sometimes
blowing hot - even on the same short trip. Seems like it is probably
blowing hot more frequently than in the past. Anybody with a similar
experience &/or any tips on what to check for? I'll take on something
if it isn't major. Thanks.

 

Any pattern to when it seems to work and when it doesn't (i.e. does it work
better when the car is at speed)?
Do you know if the compressor is running when it isn't cooling?
Are the condensor fans running ok?

 

Being intermittent it has been hard to catch & diagnose but I've
discerned no pattern either to outside temp or RPM. I am attempting
to see if compressor &/or fan is running during hot episodes.
Thanks. I would think the intermittent nature of the problem would
rule out quite a bit, such as compressor & refrigerant.

 

Update on intermittent AC cooling. When working the air is cold so
I'm not sure how it could be a low refrigerant cause. When blowing
hot air the condensor fan is still running but the compressor is not
turning. So, something is causing the compressor to not run when it
should. From my research on this it seems that it could be the
compressor clutch relay, the thermostat or the pressure switch. Any
experience or ideas on this? Thanks.

 

Further update: The fact the condensor fan runs when the compressor
fan doesn't seems to rule out the AC switch & I think but am not
certain, the thermostat (in the evaporator). I'm not clear on whether
it also rules out the pressure switch. If the compressor stops
because of a pressure reading, should the condensor fan still run?
Will a low pressure (like low refrig) trigger the switch & stop the
compressor just like a too high reading? I feel I'm closing in on
this & my chief suspect is the compressor clutch relay but want to be
sure before I start ordering parts. Thanks.

 

All systems are different, particularly the logic of when the fans run and
when the compressor runs. One thing to check if you can get to it, is there
12v at the compressor when it should be running and it is not? If there is,
can you (carefully!) get something metallic near the compressor clutch and
feel if there is some magnetic force? If so, the clutch clearance may have
become to large, it is usually easy to re-shim this. If there is no 12v,
work backwards through the electrical system. Do you have a wiring diagram?
You might find one here: http://www.honda.co.uk/car/owner/workshop.html

It's obviously not a refrigerant level problem. It's the compressor or
something before it electrically.


www.poolecool.co.uk

 

Update: I checked the refrigerant level & pressure & it is fine. One
more Q&A & I should have this figured out. If my pressure switch is
bad, would the condensor fan run & the compressor not run? Does the
system need to be evacuated to replace the pressure switch? If the
condensor fan should not be running if the compressor is not running
then my next step is to replace the compressor clutch relay which has
been my chief suspect all along. Appreciate any knowledgeable feedback
out there. Thanks.

 

Pressures for running the fan, and safety cutout, are different and have
separate sensors even if in the same body. So it could be the sensor or the
compressor (or any of the other parts you mention). I wouldn't know the
specifics of your car without looking at it. If you have a wiring diagram,
and can identify the parts and the wire colours, you should be able to find
the fault. It's either that or just change things until it works. Many
pressure switches are on shut off valves, so you can change them with only a
little loss of gas as you unscrew them, but I wouldn't be certain about
yours without seeing it. Again, if you figure out what the pressure switch
is doing from the wiring diagram, you can bypass it as a test.

www.poolecool.co.uk

 

Update: I checked the red clutch/coil lead in "failed" mode & I still
had battery voltage which proves my relay is fine. I then forced the
clutch against the rotating pressure plate (exciting - I recommend a
thin wooden stick/pole - less sparks than metal) & lo & behold, it
engaged. The gap is out of spec - not by a huge amount but it is
bigger than the outside tolerance. I guess that over time the natural
progression is for everything to wear & loosen to a wider gap.
So, it seems clear I need to pull the clutch & remove some shims.
I've never messed with a compressor clutch & there is precious little
clearance from the end of the clutch to the inner fender - maybe
3/4". I'm not sure what I'm getting into here. I don't think there
is enough clearance without pulling the compressor & then I'm not sure
you could do it without evacuating the system? Can you do this with
the compressor in place or must it be removed? I'm wondering if I
might be better off to take it to a reliable mechanic & have them do
this. I wouldn't expect there to be too much to it for them....maybe
1 hour labor or something like that? Any opinions or experience on
this? Thanks again.

 

Ok, looks like we diagnosed it. If you can get to the nut / bolt on the end
of the compressor, try loosening it - you may need to arrange something to
lock the clutch plate from turning. Then, if you have enough space, you
should be able to remove the clutch plate, and you should find some shims
which can be removed.

If you don't have enough space the compressor must come off, which means
regassing.

www.poolecool.co.uk

 

The only way to get at the end center bolt is to dismount the
compressor from the mounting bracket & move it around as much as I can
within a limited space. Just for grins I tried to test the coil
resistance. I'm using 2 Micronta meters & I'm getting right at 3 ohms
from on1 & 3.25 ohms from the other. These aren't expensive meters so
I know I can't expect high accuracy. If a coil was getting weaker,
would the resistance increase or decrease? Also, I'm not sure what
the spec is for this coil. I have a shop manual for a 96 4 cyl that
states 3.6 +- .2 ohms. I have a 96 V6 & I've already found some
differences between the AC systems. Does anybody know what the clutch
coil resistance should be on a 96 EX V6? Thanks.