[/IMG]Hi there!
I'm a new member. Just signed up because I have a problem with my A/C, or more specifically the diaphragm for the climate control. Everything works great except for when it gets hot outside, like 80 degrees F. When it's hot and I want to get the A/C to work, the air flow (as in going to the floor, defroster, panel etc.) gradually shuts down and the blower eventually sounds like it is just blowing air into a tunnel and no air at all comes into the cab of the car. The A/C works fine when it is not over 80 degrees outside, or when I first start the car up when it is cold. I'm not sure if the control for the diaphragm thingy that directs the air flow is actuated by vacuum, or electric switch, but I suspect it is by vacuum which starts leaking when something gets hot under the hood. I read manual schematics and it looks like there are a bunch of possible vacuum gizmos throughout the car, so I am at a loss trying to guess which one I need to replace ... or maybe it is electric??? Thanks in advance for your answers.
This is a great car that has been in my family since it was new. 114,000 miles driven by a little ol' 88 year old lady .... my Mom! I'm still blowing the cobwebs out of the turbo ... great fun!
Pic of car taken after being cleaned by Walter White's car wash from Breaking Bad.
[IMG=http://lookpic.com/O/i2/562/S49mMp0q.jpeg]

 

Are you thinking you are having problems with the blend door?

Check out https://www.volvoclub.org.uk/tech/se...ystem-Auto.pdf

Also there's additional info at Volvotips

There's temp sensors in the duct itself that could be the problem - are you getting a Check Engine code or see the AC/REC lights flash at any point? See if you can check for any stored codes for the climate control CPU.

Does the AC compressor stay engaged even though you don't get cold air? Its possible that your compressor kicks off on the hottest days due to heat build up - usually a sign of a clutch gap problem.

 

Many thanks MT6127 for your reply!
I am having problems with the air distribution and/or the blend door as you call it. I didn't have the correct terminology for what to call it, but it seems you hit the nail on the head calling it a blend door.
I know the compressor is not the problem because while the air flow decreases as the system gets hotter (from outside ambient air temperature increase going from around 75 F to 85 F), the air remains just as cold as when it was working at full capacity. I can also still feel cold air barely trickling out of the floor vent when it is practically not putting out any air at all. The process of air flow decreasing from full blast to no air at all can take as long as 1/2 to an hour when I am on the highway heading down to Denver which is lower than where I live and usually warmer. I find the length of time it takes to shut down air flow is a function of outside ambient air temperature change exclusively. The compressor is still working even when the air flow is fully constricted. Also, I can slowly hear the tone of the air conditioning system change from a normal sounding blower sending air into the ducts into what sounds like the blower just running at the same speed but not blowing any air anywhere. It's becomes a "hollow" sound instead of a blowing sound.
I replaced the ECC unit with a used one last year, but the symptoms were unchanged and I doubt both of the ECC units had identical problems. This is why I believe the problem is not with any sensing, but the mechanism that actuates the blend door, but I am often proven wrong about what I believe. Maybe it is the sensor that changes the air flow direction based on outside temperature? Sounds like a plausible cause, but I figured it would be sending air somewhere at least. The description of the air distribution control makes me think it only works in the auto mode, and my problems exist in all modes, both auto and manual, recirculate and outside, and any other possibility of settings. When everyone in the car is sweating, every possibility on the ECC panel is tried many times.
In the past I studied that link you sent from the manual regarding the climate control system, but got frustrated with the technical jargon and decided to post here hoping somebody that speaks manual-ese better than I can has already deciphered it out.
I have not checked any codes. I'm just now getting educated on doing that. I'm amazed on how smart that system is!
Thanks again for your reply!

 

take a look at this diagram... Volvo Climate unit, L.H.D

there's a "shutter" (#17) that is actuated by a motor and a linkage. So its possible for the linkage or the door to be jammed or the motor to be bad (I'd suspect that anything electrical should throw a code when it fails - ie draws too much current or not enough), or the temp sensors are off (essentially telling the car the air is cooler or warmer than it really is).

Do you have any issues with the heater? I'm wondering if maybe the door is allowing too much heat to mix in (Volvos use a constant flow to the heater core and regulate the air through the heater core not the fluid going into the core..).

 

Have you considered whether it's freezing up? That is what it really sounds like. Do you have any A/C gauges? Probably not. But I think if it's blocked by ice you should be able to figure that out. If the compressor never shuts off, and it's still dripping condensate an hour later, that ought to tell you.

Also, if you turn the A/C off while driving, and the air starts blowing again, you'll know for sure it was frozen.

The fresh air door may be closing, but I can't imagine why it would need to close "slowly". I think it's actually electronic if you have the automatic temperature control.

I would be willing to bet $5 on a freezup.

 

Thanks mt6127 and firebirdparts for the great replies. A quick reply would be:

for mt6127: I think I'll break down and test the codes to see if I can find any electrical issues. It has became clear to me I should have started there in the first place and I see there are YouTube vids that Robert DIY from these forums put up so I should take advantage of his willingness to share knowledge. I don't have any problems with heater though, in answer to your question.

for firebirdparts: I never thought of a freeze up! To be honest, in my 45 years of driving I have never experienced a freeze up; either with me driving or anybody else driving. I think perhaps our low humidity in the arid mountains might make it as rare as a 2" rainfall. Right now we have 30% humidity, but that is high because we have been having rains lately. Normal summer humidity when it gets hot (above 80 degrees) is around 10%. In a freeze up, does the air stop blowing altogether? I'm guessing it would since the condenser is iced up and not allowing air to get through. If during a freeze up I switched over to air from the heater, would it then blow air because air goes through the heater coil instead of the cooling coil IYHO? man, I am excited to think it is a simple problem such as a freeze up! I've always heard to turn the A/C temp up instead of turning down the air flow to avoid freeze up, and that makes sense to me. I also understand how turning off the A/C would let it thaw out too, so that is a great idea to check for freezing.
I am looking forward to sending you a nice crisp $5 bill if all I have to do is keep the system from freezing up!
Like I said, I'll run the codes when I get a chance. Right now I have a tractor stuck out in the field I need to get running again. Thanks again guys.

 

Car a/c has to be diligently protected from freezing, since the compressor capacity spreads over a very broad range.

So yeah, it'll freeze up until air stops. If you turn the heat on, nothing will happen until it thaws, and presumably it'll thaw only when you turn the compressor off. Air goes through A/C first and then reheats. However, it ought to thaw out pretty fast if you're driving with the compressor off and the blower cranking.

If I were you I would be experimenting.

If it is freezing, then the problem is the pressure switch. That is what protects it from freezing. Or you could wait for dryer weather, ha ha!

 

PS: This is wrong:
"I've always heard to turn the A/C temp up instead of turning down the air flow to avoid freeze up "

Won't work. You have to turn the compressor off.