Today’s Problem Symptoms:

This 2001 Nissan Altima AC problem does not have a code except it blew hot air. When the AC button in the dash was pressed, the compressor does not come on. Putting direct voltage to compressor clutch wirings made it come on and cold air came out.

Diagnostics on 2001 Nissan Altima AC Problem:

Since it blew cold air when the compressor was activated manually, the freon pressures should be OK but it is a good precaution to check for freon leaks.

Looking at the AC wiring diagram, the compressor gets it power from thermal protector switch followed by ac relay which is grounded by the engine control module (ecm). This ecm ground signal is applied after the ecm gets it input namely; from the tripple pressure switch sitting on top of the ac drier housing and thermo control amplifier sitting on the right side of dash by AC main housing inside the engine compartment.

This means if the triple switch is worn internally, the ecm will stop the compressor from working. The same with the thermo control amplifier. These 2 components must be looked at first before checking anything.

Solution to 2001 Nissan Altima AC Problem:

The AC triple switch contacts were found defective and was replaced as an assembly. Doing this made the AC blew cold air again.

Notes on this 2001 Nissan Altima AC Problem:

The power supply from the ac relay can be checked by checking for 12 volts at the light green wire terminal. Remember also that this ac relay is grounded by the ecm thru the red yellow wire terminal.

All these wiring connections can be seen in the 2001 Nissan Altima wiring diagram which can be explained to members of ATS subscribers in detail.

Please do not attempt to do this on your own unless assisted by a licensed automotive mechanic to prevent damage to your AC components.

Please leave your comments below if you have any Nissan Altima AC questions.

Thanks,

Richard