Air conditioning compressor staying on and not cooling

ZELLY

MEMBER
2001 NISSAN FRONTIER
3.3L
6 CYL
2WD
AUTOMATIC
212,000 MILES

The A/C compressor is staying on all the time and not cycling. It will turn off if I physical turn the A/C switch off at the dash. It is not blowing cool inside the truck. I did take some readings with the gauges hooked up. Outside temperature is 76 degrees. Gauge readings with nothing running or turned on LOW=70 HIGH=70. Running at 1000 RPM, LOW=10 HIGH=90 Not cycling. Running at 2000 RPM, LOW=3 HIGH=100 Not cycling. Thanks for any help or advice in advance.

3 Replies

AL514

MECHANIC
4,793 POSTS

Hello thanks for using 2CarPros. Both of those readings are low. You probably have a leak in the system. The compressor is staying on because of these low pressures. You will have to have someone with A/C experience to find the leak, vacuum the system and recharge it with the proper amount.

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Sunday, October 6th, 2019 AT 11:14 AM

ZELLY

MEMBER
2 POSTS

Thanks for the reply. The thing that was confusing me was that the compressor was staying on with such low pressure but I see where that makes sense now. So dye will have to be introduced into the system and a UV light used to find the leak? Also, does the system need to be running or can the leak be detected with the engine and A/C system off?

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Sunday, October 6th, 2019 AT 11:59 AM

AL514

MECHANIC
4,793 POSTS

There are a couple ways to find a leak. With the system at the proper pressures, yes dye can be used. Sometimes it's at simple as spraying soapy water on the connections and fittings. The leak will bubble out. It's best to run the system if using dye. That way the dye will circulate around the entire system. These leaks can be tiny, leaking out over time. They have the recharge kits you can buy, but it will eventually leak out causing the same problem again. Hopes this has helped.

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Sunday, October 6th, 2019 AT 4:26 PM