A/C works intermittenly-2000 Nissan Altima

Just purchased 2000 Nissan Altima. A/C would blow cold air then blow hot. Mechanic vacuumed out system, replaced expansion valve and charged system. A/C would then blow cold air then blow hot again. I changed out the thermal control amplifier; still does the same thing. Would should I do now?

Present your concern to the mechanic that worked on the system,did you not get a warranty/guaranty in regards to the diagnosis and the repairs performed?Your sisuation is called a comeback/re-check.

Granted I had a problem with a different car, but it might be worth a check. My problem was related to the electric switch that engages the clutch of the AC compressor not working, which did not allow the compressor to engage.

It’s just an idea and something you can check on your own. Run the AC on high around the block while on errands or something. While the engine is on, locate the AC compressor, which will most likely (not familiar with altima) be in line with the serpentine belt (the belt that loops and connects all kinds of pulleys). The AC compressor clutch is actually inside the pully that is attached to the AC compressor. If everything is working properly, wit the AC on high, you should see the pulley cycling between free-spinning and engaged. You should be able to see the end of the pulley spinning and then not spinning in cycle as the compressor does its work.

Once you have identified where the clutch is, if there is not cycling as mentioned, between free-spinning and engaged, then the clutch switch, or the clutch itself, might be bad.

You could probably replace the compressor and clutch yourself but you will need to take some things extremely serious. One, you have to have your system professionally purged. No, seriously, you could cause instantaneous blinding or death; both pretty serious circumstances. Two, protect your freakin’ eyes when you are under the car with remainder refrigerant possibly dripping down.

In my case, it was pretty darn easy to swap out the compressor and clutch assembly. One bold held in the high/low fittings, and four bolts that held the compressor in place.

I had a similar problem.the a/c unit was low on 134 a.and had a small leak in the a/c system.i took it to my mechanic he purged the a/c system added 134a /oil leak dye.and went back one week later to find the leak with a sniffer tool.cost 100.00 it was worth it.