A/c blows cold, then stops! WTF?!?!
08-29-2009, 08:49 AM
#1
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A/c blows cold, then stops! WTF?!?! I have a boogy monster.
The problem I'm having is that the ac works fine when you first start the car and drive for a while, but about a hour into the drive the ac vents seem to get more and more weaker. The blower is still blowing the same speed, but the air isn't coming out of any vents. It almost sounds like the air deflector, that moves according to your selection on the ac controls looses its postion and just kind of "closes" and directs the air to nowhere. If you catch it in time as the action starts to happen by placing the selector from the MAX setting to the NORM, where it pulls air from outside it seems to work well for a little longer, then eventually it "closes" the air comming into the cabin. Now you shut everthing off for a while, and turn it all back on and it works fine for sometime until the same thing happens all over again. I have replaced the ac controls and same issue.
Any help would be great!!
The problem I'm having is that the ac works fine when you first start the car and drive for a while, but about a hour into the drive the ac vents seem to get more and more weaker. The blower is still blowing the same speed, but the air isn't coming out of any vents. It almost sounds like the air deflector, that moves according to your selection on the ac controls looses its postion and just kind of "closes" and directs the air to nowhere. If you catch it in time as the action starts to happen by placing the selector from the MAX setting to the NORM, where it pulls air from outside it seems to work well for a little longer, then eventually it "closes" the air comming into the cabin. Now you shut everthing off for a while, and turn it all back on and it works fine for sometime until the same thing happens all over again. I have replaced the ac controls and same issue.
Any help would be great!!
08-29-2009, 08:58 AM
#2
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All of the doors that direct airflow inside the cabin are vacuum controlled. I'd start looking for a vacuum leak in these control circuits, starting with where it comes off the intake manifold. It could be a slight leak in one of the hoses, or a slight leak in one of the vacuum motors controlling the doors. Also where the hoses come together and connect on the back of the control valve (heat, a/c, defrost selector) in the cabin.
08-29-2009, 02:23 PM
#3
Is it possible your evaporator is freezing up? That would explain the extension of air flow time when you switch to NORM since hot outside air getting pulled in might defrost the evap for it to allow air flow for a bit more. Try putting it on vent when it happens. If it "fixes" the probem (by defrosting the evap) for a while, would tend to confirm this.
Might also relate: does your car drop water on the ground when you turn off the AC? If not, your drain tube could be clogged.
edit: http://autorepair.about.com/library/faqs/bl485g.htm
Might also relate: does your car drop water on the ground when you turn off the AC? If not, your drain tube could be clogged.
edit: http://autorepair.about.com/library/faqs/bl485g.htm
Last edited by angel71rs; 08-29-2009 at 02:28 PM. Reason: additional info
08-30-2009, 05:53 PM
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You guys have been a great help! Please let me know if your repair fixes your problem ^ It sounds like the evap is freezing up because when I put it to vent only, it seems to clear out the issue faster then turning the dial to "norm". Another fact is after a while on "NORM" it too starts to fade out and eventually stop blowing air out the vents. Then a few seconds after I turn the dial to vent, it blows.
So the evap is icing over due to low freon levels, that either when the ac compressor was rebuilt about a year ago the system didn't get enough of a charge or there is a slow leak somewhere and the freon level is getting low?
Anyone know of a good AC shop in the Tampa/Pinellas county area?
So the evap is icing over due to low freon levels, that either when the ac compressor was rebuilt about a year ago the system didn't get enough of a charge or there is a slow leak somewhere and the freon level is getting low?
Anyone know of a good AC shop in the Tampa/Pinellas county area?
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08-31-2009, 08:06 PM
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Hey Brian I have to go with Marc on this one, I can here my compressor knock when I turn on the AC and goes away when I turn it off. My car is an 01 with 10,000 miles on it. I just replaced 8 year old tires with 10,000 miles on them because they were "dry rotted", so my AC is fair game too.
09-02-2009, 07:32 PM
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yea, theres a certain amount you're supposed to have, without the proper gages and refrig...youll never know. mine did the same thing, put another can or so of freon in it, stopped making noise, blew ICE COLD and still does :-)
09-02-2009, 09:29 PM
#13
Below about 30 psig and you're going to be icing up the evaporator. It'll cool well until it freezes up because the evaporator is close to 32°F.
Keep in mind, if you've got a leak, you're likely losing oil as well as refrigerant since they circulate together. Get it fixed before you lose enough to toast your compressor and cause a BIG repair bill.
09-03-2009, 10:30 PM
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he he... Why would you evaporator freeze??? if there was a leak, your evaporator should be warm, not freezing. I would get a high side and low side reading. If the pressures are equal, your thermostatic expansion valve is stuck open. But I would leave your AC alone and leave it to the professionals........ Also, if you worked on you AC yourself, you could have OVERCHARGED the system!
09-03-2009, 10:35 PM
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he he... Why would you evaporator freeze??? if there was a leak, your evaporator should be warm, not freezing. I would get a high side and low side reading. If the pressures are equal, your thermostatic expansion valve is stuck open. But I would leave your AC alone and leave it to the professionals........ Also, if you worked on you AC yourself, you could have OVERCHARGED the system!
09-03-2009, 10:38 PM
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You must have never taken HVAC 101.... If there is a leak, the refrigerant will be gone, and will NOT RETURN. the next time he starts the ac, it will NOT blow cold, EVER AGAIN. until more refrigerant is added.
09-03-2009, 10:46 PM
#17
Of course. Whatever you say. You obviously have more experience in HVAC than I do.
09-03-2009, 10:59 PM
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09-03-2009, 11:14 PM
#19
I'm just a shadetree mechanic. I was an HVAC technician before going back to college for my Engineering degree.
09-04-2009, 01:50 AM
#20
I rarely use my AC, but I've noticed that over the last year, it started to not blow as cold. I would estimate the coldest temperature currently achievable is around 35°. Funny thing is that it actually seems to blow colder on regular AC than it does on Max AC. Another noticeable symptom is that the cold air always starts to dissipate when I come to a stop, and then start again when I start rolling. When it used to blow ice cold (year and a half ago), I remember seeing water dripping from the AC compressor area after I turn off the AC.
Where is the evaporator located? And is charging with a dyed refrigerant the best way to find a leak?
Where is the evaporator located? And is charging with a dyed refrigerant the best way to find a leak?
