Mobile Car Air Conditioning Perth recently attended a Mitsubishi in Northbridge with an unusual air conditioning problem. The system produced cool air, but it wasn’t getting properly cold. The owner also told us that the air conditioning would sometimes stop working completely.
CMM Automotive carried out a series of tests to find the cause.
Our nitrogen pressure test detected refrigerant leaking from the air conditioning Schrader valves. We replaced both leaking valves and charged the system with the correct amount of R134a refrigerant.
At first, everything appeared to work correctly.
However, we allowed the Mitsubishi to continue running. About 20 minutes later, the vents suddenly started blowing hot air.
Further diagnosis found a second fault. An electrical relay would heat up after operating for some time and then stop working.
Mitsubishi Air Conditioning Not Cold Enough
Air conditioning problems aren’t always straightforward.
The customer’s description can provide important information before testing even begins.
In this case, the Mitsubishi had two symptoms. The air wasn’t getting cold enough, and the system would sometimes stop working.
That second symptom was particularly important.
An air conditioning system that works and then suddenly stops can have an electrical or control problem. However, we still needed to test the entire system.
Nitrogen Testing Found Refrigerant Leaks
CMM Automotive pressure tested the Mitsubishi’s air conditioning system with nitrogen.
The test identified leaks from the Schrader valves.
Schrader valves provide service access to the air conditioning system. Like other seals and components, they can eventually develop leaks.
Even a small leak can allow R134a refrigerant to escape over time.
We replaced both faulty Schrader valves before continuing with the air conditioning service.
Recharging the System With R134a Refrigerant
After repairing the leaks, we charged the Mitsubishi’s air conditioning system with the correct amount of R134a refrigerant.
The system initially operated correctly.
Cold air began coming from the vents, and the repair appeared successful.
However, the owner’s original complaint included an important detail. The air conditioning sometimes stopped working.
For that reason, we didn’t finish our testing as soon as the system began producing cold air.
We allowed the vehicle and air conditioning system to continue running.
That decision helped us find the second problem.
Aircon Suddenly Started Blowing Hot Air
About 20 minutes later, the Mitsubishi’s air conditioning suddenly started blowing hot air.
We now had the intermittent fault happening while we were testing the vehicle.
This allowed us to continue diagnosing the problem.
Further electrical testing identified a faulty relay.
The relay worked when it was cold. However, it became hot after operating for a period of time. Once the relay heated up, it stopped functioning correctly.
The air conditioning then stopped producing cold air.
Why Intermittent Aircon Faults Can Be Difficult to Find
An intermittent fault may not appear when a mechanic first tests the vehicle.
The system might work perfectly for five or ten minutes. The problem may only occur once components reach operating temperature.
This can make diagnosis more difficult.
If we had tested this Mitsubishi for only a short period, we could have missed the faulty relay.
The customer may have driven away with cold air, only for the same problem to return later.
Allowing the system to operate for longer reproduced the owner’s original complaint.
Two Different Air Conditioning Faults
This Mitsubishi had two separate air conditioning problems.
The leaking Schrader valves allowed refrigerant to escape. We needed to repair those leaks and restore the correct R134a charge.
The faulty relay caused a completely different problem.
Once the relay became hot, it stopped working and affected the air conditioning operation.
Repairing only the refrigerant leak would not have solved the customer’s entire complaint.
This is a good example of why professional car air conditioning diagnosis in Perth matters.
Why We Test Before and After Aircon Repairs
CMM Automotive doesn’t simply identify one problem and assume the job is complete.
Testing the system after repairs can reveal other faults.
We check air conditioning performance and vent temperatures. We also make sure the system continues operating correctly.
This becomes especially important when the customer reports an intermittent problem.
The information the owner provides can help us reproduce the fault and identify its cause.
Mobile Car Air Conditioning in Northbridge
CMM Automotive provides mobile air conditioning diagnosis and repairs in Northbridge and throughout the Perth metropolitan area.
We bring professional air conditioning equipment directly to your home or workplace.
Our services include leak detection, nitrogen pressure testing and system performance checks. We also diagnose compressor and electrical faults.
Our goal is to find the cause rather than simply treat the symptom.
Does Your Car Aircon Work and Then Stop?
If your air conditioning starts cold but later blows warm or hot air, an intermittent fault may be causing the problem.
Don’t automatically assume that the system simply needs more refrigerant.
CMM Automotive provides Mobile Car Air Conditioning Perth services for many common and intermittent aircon faults.
We can test the system, identify the problem and explain the appropriate repair.
Frequently Asked Questions
Why does my car aircon work and then suddenly blow hot air?
Electrical faults, compressor problems and other control issues can cause intermittent air conditioning operation. Proper testing can help identify the cause.
Can Schrader valves leak aircon refrigerant?
Yes. Worn or damaged Schrader valves can allow refrigerant to escape from the air conditioning system.
Why should an aircon system run after repairs?
Running the system allows the technician to check its performance. It can also help reveal faults that only appear after components become hot.
Does CMM Automotive diagnose intermittent aircon faults?
Yes. CMM Automotive diagnoses many electrical, refrigerant and mechanical air conditioning problems throughout Perth.
