Obviously another trip to the dealer is in my future . However before doing that just wanted to see if this forum has any input .

2008 Z51 mn

after about 1/2 hour of running , a.c. stops blowing out of the vents , can hear fans still running and a.c. that is dribbling out is still cold just wont come out of the vents . If i shut the a.c. off for 10 minutes or so ( fun in the florida summertime ) and turn it back on it will start working correctly with vapor and or liquid blowing through the vents for the first few minutes or so , as if something has been frozen then given a chance to defrost ? but after 10 minutes or so of running fine it will go back to not blowing out of the vents at all .

anyone have this problem and if so , how did it giet fixed ?.

this reminds me of a similiar problem i had with a 90s ZR-1 ? you would think they would have had this worked out by now .

 

The compressor is most likely freezing over, than it is warming up and working again, as the freon is low this occurrs, but this most likley a result of a small leak as it is a sealed system and should not be low. Dealer time, they can test the system then do a check for leaks,it could be that something is getting warm then expanding then leaking as opposed to leaking when the car is cold and dormaint, cars have a few unique a/c problems that homes do not. I am not an a/c tech, my dad is a retire engineer hvac/mechanical engineer, so I hear this stuff all the time on system repairs, my bro owns a company, my uncle so it grows on ya, but since it is new, dealer, ps you can get a thermometer and drive it, time it and then go to the dealer and show them the results.

 

hardhattg:

Let me see if I understand this problem correctly, after 1/2 hr. your A/C compressor is running, but there is no air moving from the vents? If this is the case their are 2 possible scenarios - 1) fan motor for interior in somehow stopping(binding up or a switch problem) 2) refrigerant circuit is low on charge and coil is freezing up, blocking air flow. The vapor or liquid you see is condensed humidity( what we call condensation just like in a home unit). If your refrigerant circuit was very low on charge, there is a low pressure control that would shut off the compressor to avoid damage and your coil would probably not freeze up.

 

I'm betting on option 2 above. I dealt with the exact same symptoms in a '91 Camry a few years ago. I replaced leaking receiver/dryer o-rings, evacuated and recharged the system, and all was good again.

 

You probably have a low system charge thats freezing up the evap coil, or a cycling switch( if a C6 has one) Thats not working properly, I would bet a small leak that has caused a low fill condition.

 

 

I agree wit the others. Your system is low on freon causing the coils to freeze up and block airflow. I've had this happen in my last house and have ssen it on cars.

 

Great responses , thanks for all the advice . why an 08 with 1700 miles should be low on freon is hard to understand , but anything is possible .

i expect to bring the car in to the dealer tommorrow and when the problem is solved i will post the solution .

Thanks Again

 

A.C. nightmare update


Brought car into dealer , explained problem . Received a call car was done within an hour of dropping it off , Tech explained that although the freon level was actually 1/2 lb. over factory specs he evacuated and refilled th system ." should be fine " ?. I was skeptical . Within an hour or so of driving same problem almost no air coming out of the vents even on highest fan setting .

A few days later taking a chance i was driving the car and ended up calling the dealer from the road where i was forced to drive with windows down as AC was not working . told them i just wanted them to have a record of it and that i would get the car back to them ASAP . they responded by saying there was no way to make a record of it and that i should just bring the car back in .

a few days later brought the car back in dropped it off and received a call later that day . They cannot duplicate the problem at the dealership . I told them it starts on the interstate after driving apx.1 hour it will start diminishing and after two hours you have no air at all . The service advisor went on to tell me that the service tech , shop foreman and service manager all agreed that if its still blowing cold after sitting at the dealership idling for three hours , that it is fine . that at idle is when a problem would surface, not driving . WTF does this mean , I am making it up ?. My son and i are driving around sweating our as___ off an they are telling me they decided its ok ?

Trying to keep my cool and get my car cool again i volunteered to take some time off work and come down to the dealership and drive the car for an hour or two until it stops working and then bring it in . I actually did this and drove up and down the interstate for about an hour and a half and sure enough the fan started dying , not to its worst level , that happens after 2 hours or so . so i called the dealership told them i had duplicated the problem and please have tech ready to look at it because as i slow down and the car idles it often will start blowing again . Well you can guess what happened , the dealership is about 4 miles from the interstate, lots of traffic lights , and about 1/2 mile from the dealership the air starts blowing again . I get to the dealership and they are all smiles , kind of like well nothing we can do .

this is where it gets scary . I tell them i tried but apparently a tech will have to drive the car himself as by the time we get back to the dealership it will clear it self . I have to explain that i like to take longer trips with the car and would actually like to be able to have a.c. in my 2008 black corvette in july in florida ! They tell me they cant possibly put a tech in the car for that long a time , he is too busy and gets paid a flat rate ? They tell me the best they can do is have one of the techs drive the car personally and take it home for the weekend ? I am not one of these guys that write down the mileage when servicing the car etc... but the entire weekend the cars goes who knows where ? i tell them i am uncomfortable with that and they tell me nothing they can do then . I get a little upset realizing i now have a car i wont be able to use and a dealership that is telling me there is nothing they can do . i mention attorneys etc... and the service advisor says ok we understand your frustration , bye bye . Before leaving i decide to go in and talk to service manager who was very helpful when i bought my 06 Z06 in and had so many problems with . After consulting with her service advisor in her office she comes out and explains to me how she is understaffed , again how the techs get paid a flat rate and there is no way she can let him spend a couple of hours driving my car . she says she will put a lube person in the car to drive it and bring it back to the tech . I point out how i just did that and by the time you get back to the actual dealership it will probably clear up , that someone who knows how to evaluate the problem has to be in the car . she says thats impossible , all the while my son is next to me whispering in my ear " this is why you buy a porsche " ,

she convinces me to leave the car with her and she will see if they can work out some sort of recorder on the a.c. and let the lube guy drive it around . i agree and leave but i am not very optimistic .

any ideas from anyone would be appreciated and i apologize in advance for the length of this post .

Not that it makes any difference but i have bought close to a dozen vehicles from this dealership and the highest price vehicles chevrolet makes at that , three just within last 12 months .

 

Lets see if we can narrow this down. So, after it is starting to reduce the air flow out of the vents, it is still cold, correct? Just a loss of air flow out the VENTS, is the air coming out any other area, heater vents, defroster?

When it is running normally, do you see water from the evap. drain on the firewall dripping on the ground? The Blower Motor sits on the bottom of the case, I wonder if the motor cage is icing up? After it sits, water melts, and starts up again, that would explain the vapor mist.

When this happens, can you pull over, open the hood and check the compressor and see if it's still engaged?? Would you know what to look for?

A low charge won't freeze the system up, possilbly a bad cycling switch could though.

 

Is the A/C set on auto? After the inside of the car gets to the set temp.the fan slows down. Is the pass. side A/c on the lower temp?

 

holy buckets, I'm not trying to waste your money, but it's obvious to me. They can't duplicate it, and you can't bring it to them doing the problem.

Therefore, strike a deal: the tech takes it for 2 hours at his flat rate. If it acts up and he can figure it out and fix it, you credit his time driving the damned thing around at least 50% or maybe even 100%. It's a warranty issue, right?

Now, you got the problem solved, the tech gets paid, the dealership solves your problem and gets reimbursed by/for warranty, etc.

C'mon, let's get creative, even if it means money out. If I'm wrong, tell me where; I really want to know.

And by the way, as Chev tech said: are you sure the dealership has no manual that says, "if this is happening, check this?" Kinda like FAQ or Trouble Shooting, etc. If they don't, I find that almost incredible. Ask the Service Manager.

 

Might be the expansion valve.

 

UPDATE :

Dealer called late Friday afternoon , said they were able to duplicate the issue by a combination of driving it around for a while and sitting in the car revving the motor for a while . Said it looks like an evaporator problem , and they have ordered one . should have car back by Tuesday .

will let you guys know if this solved the problem .

 

At least they took the time to finally prove you're not a nut. Hopefully they fix it.

 

received a call from the dealer today , they replaced the evaporator , drove the car around for a couple of more hours ( good thing we have 100k mile warranty ) and the a.c. stopped working again . they have no idea what to do next . They are In contact with GM to discuss what to try next and there is talk of a TSB resulting from this problem .

will post whatever happens next , at this point no one seems to know .

if they keep the car much longer i may have to look to lemon law the car , i would just like to have one that i could drive .

 

Crap, I thought that was the solution, too. And you were doing well at the drags with the car. Tell us how it turns out.

 

The Evap. core was a stretch, I guess possible, but not likely. You said the air is still cold, but not much air flow, so are you dealing with a blower motor issue? If you were to turn the A/C off, and just run the fan, can you get high blower speeds? Or is the air coming out all the vents, top and bottom, so there isn't much to come out the dash vents.

If the air is still cold, I don't see how it's going to be something in the compressor side of the system. Seems more likely a dash, blower module issue.

 

Could the flaps/valves leading to the vents be partially closing? Or not fully opening?

 

This probably won't help but I'll mention it anyway...

There is a TSB for 05 vettes because some were overfilled with Freon from the factory. This would manifest itself by the AC compressor going off on high pressure - and the ac would get hot and fast. But it would still blow out the vents, just hot like if you had the vent on. This would happen on really hot days here in FL, usually sitting in traffic. After a while driving or sitting it would be normal again. I had Kelley Chevrolet look up the TSB for me, adjust the Freon level as it says, and it's been fine ever since.

I can't imagine you are high or low on freon after getting a new evaporator but thought I'd mention this to you. Good luck and keep us posted please!