Assist with AC Troubleshooting
08-16-2015, 02:15 PM
#17
Drifting
"This is at 70mph at 85-90 outside temp (strong sun)".
For a stock R12 system, 42F is pretty good; you will
have losses between the evap and the vent, just like
losses between the flywheel and tires.
You indicated you had 30 inHg on the low at idle.
THX, CG.
So that tells you that you have a cold evap core.
You can't get much more heat transfer with the
stock evap so the thermostat will keep asking for
more. And, I'd suspect you still have some air
in the system (email to chat about that).
If you are happy with that result, I'd suggest
just a set of barrier hoses, orings, binary pressure switch,
drier, upgrade the evap, toss in a Kuehl vent, maybe
open up the compressor while the system is empty
and inspect the bores, pistons and wobble plates,
if all is well toss in a new seal and oring set.
If you want colder, feel free to drop an email.
For a stock R12 system, 42F is pretty good; you will
have losses between the evap and the vent, just like
losses between the flywheel and tires.
You indicated you had 30 inHg on the low at idle.
THX, CG.
So that tells you that you have a cold evap core.
You can't get much more heat transfer with the
stock evap so the thermostat will keep asking for
more. And, I'd suspect you still have some air
in the system (email to chat about that).
If you are happy with that result, I'd suggest
just a set of barrier hoses, orings, binary pressure switch,
drier, upgrade the evap, toss in a Kuehl vent, maybe
open up the compressor while the system is empty
and inspect the bores, pistons and wobble plates,
if all is well toss in a new seal and oring set.
If you want colder, feel free to drop an email.
08-21-2015, 11:50 AM
#18
Before you start pulling things apart, once again, troubleshooting the AC system starts with basics, such as pressure and temperature readings and from those results you start looking at specific components.
If you want to do it the hard way, read this 100+ page thread.
Fixing things the hard way
Had the car owner simply performed a few common tests, such as observing the pressures and temperatures, and used a few common tools suggested to him, he would have realized early on what the problem was.
Once again, starting with the observation that your high side pressure was excessive at 90F with factory spec charge of refrigerant, the first thing you need to consider is ambient (air) gases mixed with the refrigerant which drive up the pressures....... you do this before you start tearing out an evaporator box. Is your evaporator core dirty? Maybe, however you got other issues to review first.
The famous 100 page thread has some very good comments and contributions made from experienced 911 owners, and you will also read
some far end comments. With patience you can sort through the logic.
If you want to do it the hard way, read this 100+ page thread.
Fixing things the hard way
Had the car owner simply performed a few common tests, such as observing the pressures and temperatures, and used a few common tools suggested to him, he would have realized early on what the problem was.
Once again, starting with the observation that your high side pressure was excessive at 90F with factory spec charge of refrigerant, the first thing you need to consider is ambient (air) gases mixed with the refrigerant which drive up the pressures....... you do this before you start tearing out an evaporator box. Is your evaporator core dirty? Maybe, however you got other issues to review first.
The famous 100 page thread has some very good comments and contributions made from experienced 911 owners, and you will also read
some far end comments. With patience you can sort through the logic.