I have just bought an early 2017 CX-5. The air conditioning system just blows hot air. Had it vacuum tested and filled with gas today and there is no change. The gas has not leaked.

What are the best things to check next?

 

Welcome to the forum

Welcome to the forum


Well, I am not sure who filled your AC system, but they should have checked for several things before just filling it. If any AC system is needing refrigerant, then there is a leak which is a problem that first needs to be found and corrected.

Take it to a shop that Services AC system or the Mazda Dealership.

Expect at least 1-hour diagnostic labor fee. Most AC system problem when refrigerant is needing average cost for repairs run between 300-1000+ USD.
So don't be surprised...

Diagnose AC problems REQUIRES the proper HVAC System gauges and other tools and equipment for testing. It is NOT a DIY friendly service. But if you feel you are competent then get a Factory Service manual to read how to diagnosis the HVAC system or have someone print you a service procedure in a Auto service program like ALLData (they require a fee for single platform and model access limited subscription)

 

Make sure the compressor is engaging properly.
If not, one of your AC pressure sensors could be bad if vacuum test and gas fill was done properly.

 

Well I never like when anyone just fills a low AC system because it means a leak and that freon will continue to leak and into the air.

I forget as you did Lobstah that on that and our MAZDAs if the radiator fans do not actuate when HVAC is AC or defrost setting mode the AC will not blow cold air work!

 

It went into Kwik Fit. They rigged the A/C up to some machine, did a vacuum test and then filled up with gas.

No leaks detected but the A/C did not cool after the work.

There is a 7.5A Fuse, which I checked and a relay which I swapped.

 

I did a bit more digging and found that the relay clicks on when I turn on the A/C but when I link the relay output, I cannot hear the compressor clutch click on. Does anyone know if the relay output wires directly to the compressor clutch?

 

You are not reading what I posted?

It is very easy to mess up components on the electrical system by DIY.
The service facility you took your Mazda has no idea what they were doing if they did not find a problem filled your low refrigerant and then charged you for the service leaving with no functioning AC!

The vacuum pump testing system does not always find small leaks in a few minutes and must be on the test machine for 20-30 minutes. So ask yourself did they do that?
Point being for internet advise I read this:
The AC does not work.
The fans have not been confirmed working when the AXC setting, and blower motor is working.
There is no found apparent refrigerant leak based on low refringent and needing to fill the AC system .

I strongly suggest if you do not have the proper HVAC testing equipment that you find a shop that specializing in HVAC service.

 

I do understand. I am an electrical engineer by trade and I am not tackling any of the HVAC system. It appears that the fault is in fact that the compressor clutch is not engaging when it is energised.
I have obtained a wiring diagram for the Mazda CX-5, so I can see that the relay output does indeed go to the clutch.

I can also confirm that the call for A/C works, because the relay is activated by the control system.

I took my car to a non Mazda A/C repair shop. They did the vacuum test and charged the system. The pressure held up, confirmed by the fact that the control system is trying to activate the clutch.

Mazda want to charge me £80 to do the diagnosis work, which I have done. If all that needs changing is the clutch then I can get that done by a motor mechanic.