Evaporator Sensor Fault?

travis · Postby **travis** » Mon Dec 21, 2015 11:45 am

Hi All,

Just wondering on your thoughts on this. In the middle of summer it hasn't been pleasant with the AC switching off suddenly!

I have narrowed it down to the evaporator temp sensor, photo below. The probe penetrates the evaporator housing, I have read that when the temp inside falls below X degrees the sensor will trip and stop the AC compressor, when the temperature warms up again the sensor will "reset" and the compressor will run again. This is normal operation.

My problem is that the sensor does not "RESET", so the AC never comes back on after tripping the first time. Turning the AC switch on/off doesn't help either. The only remedy i have found is to reach behind the glove box and "jiggle" any one of the two terminal connections on the sensor. As soon as i do that the compressor runs again until the next trip.

Is there a way to test the sensor (i have a multimeter)? Is there an easy way to replace or will the entire evaporator unit need to be removed and opened? This appears only to happen on the hottest days, does the heat have an affect on the sensor (which is outside of the evaporator) resetting? The system has plenty of gas, no leaks.

Thanks.

manga_blue · Postby **manga_blue** » Mon Dec 21, 2015 12:07 pm

Mazda list the sensor as a separate part, so presumably it's replaceable. It's 61-J20 on page 6150 of th NA8 catalogue. This translates to part no NA01-61-J20 "Thermostat, cooling unit".

Amayama don't list it but a google search for that part number will find you plenty of other suppliers who do. Just a question of finding someone who'll ship and paying around $70 plus P&H

manga_blue · Postby **manga_blue** » Mon Dec 21, 2015 12:16 pm

Also this:

travis · Postby **travis** » Mon Dec 21, 2015 12:31 pm

Thanks for the part number and test procedure manga_blue!

Though I am confident the switch will open below 0 degrees, it is the switch closing again when the temp returns above 0 degrees that has me suspicious. Anyway i will do the test if I can remove the sensor. With the dash still in place, can the bottom half of the evaporator housing be removed easily to allow the probe to be removed? As it does not appear to an easy task with the dash still in place, has anyone done it?

manga_blue · Postby **manga_blue** » Mon Dec 21, 2015 1:06 pm

No problem. My own A/C had been underperforming over the last few days so I was looking for test procedures already. I think my problem is mainly the typical hot air leak from the engine into the air collector box, so I've ordered a new seal for that. If that doesn't fix it then it's probably just gas, which is sort of what you'd expect after 20 years without re-charge. Good luck with yours.