AC blows hot, compressor working,

[nicv21]

2001 Pathfinder, AC blows hot, like the heat is on, Blend door actuator works, cabin temp sensor tests ok, any help?

[04pathse]

low on freon?

[nicv21]

low on freon?
Low side hose from the compressor is cold

[VStar650CL]

Make sure the blend door actuator key isn't stripped. If it is, the motor will turn but the door won't move.

[nicv21]

Make sure the blend door actuator key isn't stripped. If it is, the motor will turn but the door won't move.

I took the actuator off and cycled the door manually, I can hear it open and close. The air changes from floor to vent to defrost

Is there another door that blocks the evaporator? I can reach under the plenum on the pass side and feel its cold

[VStar650CL]

Is there another door that blocks the evaporator? I can reach under the plenum on the pass side and feel its cold

No, there shouldn't be anything else in the path. The only other cause we see is, on some models the evap is below the heater core and water from a blocked drain can drown the evap. However, that also causes a reduction in airflow when in the "cold" position. Did you check the keyway on the door, though? The door may be free but it won't move if the keyway on the door or key on the servo are rounded off or stripped.

[nicv21]

I am going to put the gauges on it tomorrow and see what the pressures are, just to eliminate another variable.

[nicv21]

Put the gauges on and the pressures are good, 150 psi high side, about 30 low, does not go into a vacuum on low when you rev the engine, so no blockages. So its time to rip it all apart and see what's what.

[04pathse]

time to rip it all apart and see what's what.

before you do that, did you look at the troubleshooting section in the FSM?
Also it looks like there is a self-diagnosis test you can run that might be helpful, instructions
are in the fsm

https://www.nicoclub.com/service-manual ... 1%2Fha.pdf

[mdmellott]

Make sure the blend door actuator key isn't stripped. If it is, the motor will turn but the door won't move.

I took the actuator off and cycled the door manually, I can hear it open and close. The air changes from floor to vent to defrost

Is there another door that blocks the evaporator? I can reach under the plenum on the pass side and feel its cold

There are actually three door motors in the HVAC system. The evaporator always has air passing through it and is never blocked. The door you are describing here that changes air flowing to the floor, vent, and/or defrost is controlled by the mode door motor, which is operated by the air flow direction knob. The mix door is the one that seems to be stuck open, fully exposing the heater core to the air flow and making your system always blow hot air. The mix door motor or its linkages to the mix door may not be allowing the system to blend the air flow properly. The mix door motor is operated by the temperature control knob. The other motor is the intake door motor which operates the door to recirculate your cabin air or bring in air from outside.

[mdmellott]

time to rip it all apart and see what's what.

before you do that, did you look at the troubleshooting section in the FSM?
Also it looks like there is a self-diagnosis test you can run that might be helpful, instructions
are in the fsm

https://www.nicoclub.com/service-manual ... 1%2Fha.pdf

Absolutely! Check out the FSM first so you know where all the bells and whistles are located and how to troubleshoot the issues. I also just realized, after looking at the '01 manual, my '02 has control knobs for air flow direction and temperature but your '01 may not, depending on what model you have (LE, SE, or XE). Mine is more manual-mechanical as opposed to electro-mechanical controls.

[VStar650CL]

There are actually three door motors in the HVAC system.

Four if the OP has Auto A/C, there will be separate mix doors for driver and passenger.

[mdmellott]

There are actually three door motors in the HVAC system.

Four if the OP has Auto A/C, there will be separate mix doors for driver and passenger.

Or just one. Now that I have looked at this in more detail, the models with manual control knobs for air flow temperature and direction are purely mechanical for operation for the mix door and mode door. There are some electrical elements to the controls put those doors are opened and closed solely with cables and levers, pulled and pushed by rotating the knobs. This should be an easy fix to find the missing link, so to speak, if it's a manual knob controlled model. Check out pages HA-181 and HA-183 for the cable a lever controls for these two knobs. https://www.nicoclub.com/service-manual ... 1%2Fha.pdf

[VStar650CL]

Or just one.

Lol yep, or zero if it was an old Versa. The OP said he popped off the actuator, so without looking at the ESM, I'm assuming his is electrical.

[mdmellott]

Lol yep, or zero if it was an old Versa.

I miss my old '69 VW Beetle. The only motor in it was the 4cyl flathead. No radiator. No oil filter. No A/C either but the hot air blown off the exhaust manifolds into the cabin kept it warm as toast inside during the winter.

[VStar650CL]

I miss my old '69 VW Beetle. The only motor in it was the 4cyl flathead. No radiator. No oil filter. No A/C either but the hot air blown off the exhaust manifolds into the cabin kept it warm as toast inside during the winter.

Not to mention you could drop the whole engine and drivetrain in ten minutes whenever those air-cooled pistons gave up. Had a buddy in college with a Microbus that had 375K on the clock, but he'd never mention that it was rebuilt 5 times.

[Mike W.]

I miss my old '69 VW Beetle. The only motor in it was the 4cyl flathead. No radiator. No oil filter. No A/C either but the hot air blown off the exhaust manifolds into the cabin kept it warm as toast inside during the winter.

Flat 4, OHV, not flathead 4.

Not to mention you could drop the whole engine and drivetrain in ten minutes whenever those air-cooled pistons gave up. Had a buddy in college with a Microbus that had 375K on the clock, but he'd never mention that it was rebuilt 5 times.

I was into aircooled VWs once upon a time. Living at the time on dirt roads I was so proficient at replacing piston rings one time I did a ring job, then didn't even start it up before embarking on a 500 mile trip. A couple of hours, almost like an oil change. I'd love to drive an old bug or bus again. Briefly.

[nicv21]

Thank you all for your reply's ! It is a 01 Pathfinder LE It has electronic push buttons for the temp control. SO the fact there is another door make sense and the heater core is the one exposed as referenced by MDMellott. i will delve further into the Abyss of schematics!

FYI all, I am a mechanic who worked on Jags and Ferraris back in the day, I closed my shop in 89 because the new diagnostic equip was out of reach. I too long for the days of the simple mechanical controls. I can set up a V12 Ferrari with 6 X 2 bbl's Weber's by ear (and still can!) But this plug and play BS just annoys me

[nicv21]

Four if the OP has Auto A/C, there will be separate mix doors for driver and passenger.

Or just one. Now that I have looked at this in more detail, the models with manual control knobs for air flow temperature and direction are purely mechanical for operation for the mix door and mode door. There are some electrical elements to the controls put those doors are opened and closed solely with cables and levers, pulled and pushed by rotating the knobs. This should be an easy fix to find the missing link, so to speak, if it's a manual knob controlled model. Check out pages HA-181 and HA-183 for the cable a lever controls for these two knobs. https://www.nicoclub.com/service-manual ... 1%2Fha.pdf

MD Mellott you win the prize! I took out the mix door actuator, and cycled the door by hand and voila! the A?C blows cold! Now I have to figure out it the actuator is bad or one of the sensors. I cycled the temp from 65 to 80 and back down again and the actuator did not respond, and it does NOT move by hand, IDK if it is supposed to.

[VStar650CL]

No, it's a worm-drive gear motor and shouldn't move by hand. Try moving the temp adjustment to the extremes (usually 60 and 90). Those are "overrides" that tell the system to ignore the sensors and just make it as cold or hot as possible. If you still get no motor movement then the actuator is bad, if you do get movement then chances are a sensor is faulty.