Strange AC problem

Paul, one quick check to see how well the compressor is working is to touch the low pressure line (below the inverter coolant reservoir) with your hand, after the AC has been on for a while. The low pressure line should be very cold and you may see water condensation dripping off the line, from moisture in the air. Of course another check is to look at the sight glass, where you should not see any bubbling while the compressor is running, but when the compressor cycles off then you should see some bubbling as the pressure in the system diminishes and the fluid refrigerant changes its state to gas due to the lower pressure in the system.

If there is any concern about something stuck in a vent, just pull the vent out by exerting a horizontal force, with your two hands above and below the vent in question. That works with the two vents on the far sides. To pull the vents surrounding the MFD the adjacent black plastic panels may be in the way. If so you would have to first pull the side vents, then remove the plastic that is impeding removal.

 

Great info Patrick ( as usual). I retrieved two pencils, had loads of fun put it all back together. Coolant bubbles are just as you say and low side measures @55 F though I seem to remember it being much colder before? I better check the pressure


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Hello,

I have a 2004 Prius with 216k miles. The AC has stopped functioning correctly. When I start the car in the early part of the day, the AC will run for a little while. As I continue to drive, though, it peters out until there is hardly any air blowing or none at all. After it has dwindled, if I leave the AC on a higher setting, a clicking noise can be heard from the passenger side of the dash. Once the AC is turned to a lower setting, the noise is no longer audible. Can anyone offer any reasoning as to why this is happening?

Sincerely,
Karla

PS - It's beginning to get a little too warm and humid in southern middle TN to be driving with no AC!

 

there's probably debris in your cabin air filter, you need to change it and clean out the fan in the area. This is located behind your glove box.

 

Thanks for a speedy response JC91006! I have tried that, though, and am still having issues.

 

did you clean out the fan? It's the area under where your cabin air filter sits. The entire area is like a bowl to collect leaves and debris that can make noises.

 

I just did that. There was a leaf in there, but it did not help. The fan is trying to turn, but cannot as if it is stuck on something. The clicking noise seems to be the fan trying to turn.

 

Unless there's still something stuck in the blades of the fan and keeping it from turning (little pebbles), you may have to replace the fan.

Have you tried turning it onto HIGH while the filter is off? see if you can hear anything click/move around.

 

I did try turning in on without the air filter in. The fan was trying to move, but could not.

 

Yeah you may have to replace the fan, they can fail like any other mechanical part.

 

While the Prius is IG-OFF, you could try removing the cabin air filter, then reaching your hand down to spin the blower fan blades to determine if there is an obstruction or some other reason that the fan is not spinning. If that doesn't help then replace the blower motor as previously suggested.

 

While that is probably a really good guess at why the fan is not turning........it could be something else.....like a failure of the electronics that controls the fan speed. If the fan is not too expensive and not too hard to replace, I guess I'd take the chance.

 

True, the AC amplifier would be an alternate potential failure point.

If the OP has a voltmeter, the voltage could be measured at the fan terminals when the fan has one of its intermittent periods, to see if voltage is present while the motor is not spinning. If voltage is present then the fan is bad. If voltage is not present when it should be, then the AC amplifier (or associated wiring harness) is bad.

If the OP has an external source of 12VDC power, that external source could be applied to the fan terminals to see how long the fan will run while a known good power source is applied.

 

I had this problem as I drove up 8000 ft to salt lake city got a new blower there for $300 and installed it in a parking lot. The bearings were out due to getting dirty (my bad should have cleaned that filter more)


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