Pacino84

Hello people,

I have a 2010 C300 with about 70k that I bought used. My AC just failed this week. It only blows warm air. I checked with a mechanic. He checked it with the engine on, the AC on full blast and here are his observations:

-The compressor works well.
-The cold pressure reading is 75-80 but should be around 30-40.
-The hot pressure reading is 150-180 but should be around 200-250ish

Based on this he thinks the expansion valve needs to be replaced. I am thinking about getting a second opinion but I was curious if anyone had a similar problem in the past and how much they spent changing the ac expansion valve. or if it could be something else.

From the look of it, expansion valves are not expensive so I will be reasonably glad if this is the only issue. I read somewhere that it could also be a blown fuse but I forgot to ask the mechanic to check it for me. I could check it but I am not sure which fuse controls the AC in my car :-(.


Thanks

Plutoe

Your terminology is all screwed up is cold= low pressure and is hot= high pressure or what and was the high pressure gauge fluctuating allot??

Pacino84

Oh Sorry, I am not really good at the lingo. So yes, hot is high and cold is low. I don't think the high pressure gauge was fluctuating a lot. I just couldn't remember the exact reading on it so I gave the estimate based of memory. However, the mechanic seemed convinced that since the low pressure reading is high and the high pressure reading is low, then the expansion valve must be at fault. I am not really AC or car savvy so that's why I here.

Thanks

Plutoe

You do not need(no fluctuation) an expansion valve---the high should be >210. Evac the system(hold) and recharge with the correct amount of refrig!

IGB

I agree...

If your compressor is working fine, then you're most likely looking at recharge because for the AC to work properly, it needs to be @ 80% or higher of the normal level. ("Normal level" = 590g of R134a)

And of course, before a recharge, I would insist that they determine how much refrigerant is in the system. And if it is in fact too low, then I would also insist that they do a leak test before the recharge.

Pacino84

Hello,

The guys at Pepboys evacuated and recharged my system on Friday. The added a die in the system as well to track if there would be any leak. I returned there Monday and they could not see any trace of a leak. So I am gonna guess that the system just needed an evac-recharge?

Thanks