2004 MGM LS weak A/C even after O-ring replace on EATC
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From: Arizona
2004 MGM LS weak A/C even after O-ring replace on EATC
I changed the O-rings on the EATC unit on the misses 2004 Mercury Grand Marquis today. The problem was that the A/C would stop blowing periodically while under load, acceleration etc, and sometimes it would be going out the defrost when this occurred. Sporadically it would still provide bursts of cold air from the vents. Well, it's 112 degrees today and she has to drive to work in this heat so I attempted and completed the O-ring replacement with the McMaster 007 orings. (I will post pictures later if helpful).
When I removed the EATC it had vacuum to the black line with the EATC removed and when I disconnected the vacuum manifold it did hiss.
Get this, when I hooked everything back up and ran the unit, it performed perfectly! I ran Max AC, Normal AC, Floor, Vent, Floor/Def, Def everything...I put the trim back on and we showered and went out for breakfast. We made a stop along the way and she was idling the car while I went inside a store. When I came out the air was no longer blowing out the vents.
Eventually the air resumed blowing even more sporadically and weakly than prior to the o-ring replacement, and one clue is I can hear what sounds like a bicycle in the spoke vaccuum fart somewhere I assume along the center firewall. (It is still too hot for me to go start it up and look but for now it did not sound like the picket-fence farting noise was inside the car).
Being that the A/C vacuum check valve YG-353 is located there, I am wondering if a failure on its part would cause this kind of noise. I have seen one video online where a gentleman pointed out the check valve location along the firewall but I haven't seen much detailed info on how to best access it (from the top no floorjack here).
I have the workshop manual printed for the pinpoint test and I can try to test pressures with my Harbor Freight brake bleeder pump/gauge if I can access the check valve.
Sidenote - I also saw one youtuber claim to test the check valve by locating a capped vac line (for the parking brake?) somewhere by the driver kick panel and hooking it up to a gauge. That would be an easier location for me to try to check if that works for my 2004.
Just wanted to see if anyone has any ideas while I wait for it to cool down outside. My choices at this point would be to order a refurbed EATC and wait for it to ship or find a mechanic on Monday to run through all of the diagnostic steps if I don't catch a lucky break soon.
The last thing I want at this point is to have to remove the EATC and its vacuum manifold again because there are only so many times I can get lucky enough to not drop the nuts down the console or torque too hard on a vacuum line etc.
Other possible helpful (or irrelevant) clues include one time I nudged the fan speed wheel up and the air actually blew harder (then wondered if the potentiometer switch or the servo inside the EATC could be roached but doubt that's my main problem) and once when it stopped blowing I got it back on by switching to the floor setting and then back.
Thank you for your input,
MGM
When I removed the EATC it had vacuum to the black line with the EATC removed and when I disconnected the vacuum manifold it did hiss.
Get this, when I hooked everything back up and ran the unit, it performed perfectly! I ran Max AC, Normal AC, Floor, Vent, Floor/Def, Def everything...I put the trim back on and we showered and went out for breakfast. We made a stop along the way and she was idling the car while I went inside a store. When I came out the air was no longer blowing out the vents.
Eventually the air resumed blowing even more sporadically and weakly than prior to the o-ring replacement, and one clue is I can hear what sounds like a bicycle in the spoke vaccuum fart somewhere I assume along the center firewall. (It is still too hot for me to go start it up and look but for now it did not sound like the picket-fence farting noise was inside the car).
Being that the A/C vacuum check valve YG-353 is located there, I am wondering if a failure on its part would cause this kind of noise. I have seen one video online where a gentleman pointed out the check valve location along the firewall but I haven't seen much detailed info on how to best access it (from the top no floorjack here).
I have the workshop manual printed for the pinpoint test and I can try to test pressures with my Harbor Freight brake bleeder pump/gauge if I can access the check valve.
Sidenote - I also saw one youtuber claim to test the check valve by locating a capped vac line (for the parking brake?) somewhere by the driver kick panel and hooking it up to a gauge. That would be an easier location for me to try to check if that works for my 2004.
Just wanted to see if anyone has any ideas while I wait for it to cool down outside. My choices at this point would be to order a refurbed EATC and wait for it to ship or find a mechanic on Monday to run through all of the diagnostic steps if I don't catch a lucky break soon.
The last thing I want at this point is to have to remove the EATC and its vacuum manifold again because there are only so many times I can get lucky enough to not drop the nuts down the console or torque too hard on a vacuum line etc.
Other possible helpful (or irrelevant) clues include one time I nudged the fan speed wheel up and the air actually blew harder (then wondered if the potentiometer switch or the servo inside the EATC could be roached but doubt that's my main problem) and once when it stopped blowing I got it back on by switching to the floor setting and then back.
Thank you for your input,
MGM
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