Air conditioning service issue

Hey all. New here so hope you don’t mind me asking for a little advice.

I’ve got a Mazda CX-9 (2009) and it had a full service a couple of weeks ago, which included a coolant flush.

The day after we got the car back, the air conditioning system started being temperamental - ie it would blow out cold air, but after about 8-10 minutes the pressure would drop and after another few minutes, the system would stop blowing out air altogether. It’s got worse now to the point that we only get 1-2 minutes of cold air (at most) before the system conks out.

Anyway, I called the garage yesterday and explained the problem and the first thing he said to me was “well it wouldn’t have been anything that we’ve done” which annoyed me because he has absolutely no way of knowing that without inspecting the car… anyway he’s talking about degassing the system and talking $$$…

So I’m taking it in next week and I just wondered if anyone might have any advice as to what possibly could happen from a coolant flush that might cause the AC to stop working? I’ve no issue paying for a fix if it is a separate problem, but I’m not keen to start forking out if the problem is down to something that they have done.

Very grateful for any advice as to what I should be looking out for.

Offhand, I can’t see a service or coolant flush having anything to do with faulty A/C operation.

There are a number of reasons why an A/C can go a bit wonky at any time. The first step should be to connect the A/C gauge set and find out what’s going on with both high and low side pressures.

They should not be talking about “degassing” the system at this point without hooking up the gauges. The proper term for “degassing” is “evacuate” the system.

The car is 10 years old and that’s about the point where refrigerant leaks and so on occur. No way of knowing without having info about system pressures.

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Yes he does have an idea, and a good one at that. Unless an A/C service was done, he would not have touched anything A/C related. Now back to your description. Does it stop blowing cold air or does it stop blowing any air at all? What pressure drops, and how are you measuring it? Manifold gauges on the A/C ports? If the air gets warm but is still blowing that suggests low or no refrigerant. If no air is blowing at all that suggests a blower problem. Completely different. But still not connected to your original service.

I just didn’t like him getting defensive when all I was doing was explaining the problem and that it started the day after we got the car back. For the average Joe such as myself who doesn’t know much about cars, it doesn’t present well from a trust perspective. All I wanted him to say was “OK we’ll take a look at it”.

Anyway, I’m off on a tangent, it’s not that important.

They did work on the cooling system - according to the report they did “labour to drain system & refill coolant, pressure test & check system integrity, roadtest and report”. If everyone here’s happy that this couldn’t be enough to cause a fault to the air conditioning, then I’ve got the answer that I was looking for

In terms of what’s happening - let’s say for example, I have the cold air con up to full whack - it will blow at full power for a short period of time (couple of minutes most), then the pressure of the air pumping in to my face will weaken, the temperature gets warmer (not WARM, but a more neutral kind of temperature), before stopping altogether within a matter of 60 seconds or so. If we leave the air con turned on, then there is a whirring sound, but no air coming out at all.

Thanks for both of your replies

This sounds like a coolant system drain and refill- as in engine coolant. This is not the same as refrigerant that makes for cold air. Did the shop mess with the air conditioning system at all?

I’m still not completely clear:
Does the air stop blowing? like no air out of the vents at all?
Assuming this is what you mean, as that is what it sounds like- this could be a couple things:
-A faulty blower
-a faulty blower resistor
-not enough air passing over the a/c evaporator causing it to freeze up, literally. So it actually forms a layer of ice on it, preventing any air from flowing through it. This would be gradual (which is what I think you are explaining,) and eventually no air flowing at all.

a way to test this:
Take the car for a drive, and crank up the a/c. When it stops blowing as you are describing, turn the dash controls to blow heat. The car should shift the air from blowing over the a/c evaporator to blowing over the heater core. If your evap is freezing up, then air should start blowing again as the air is going through a different vent inside your dash.

If turning the heater on makes no difference, and you still have no air blowing- then I would look a the blower or resistor being an issue.

Sounds a lot like automatic temperature control. Does your car have this feature? If so, did it inadvertently get turned on versus being in manual mode previously?

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