I have a loud grinding motor noise that seems to come from near the windshield under the hood on the passenger side but it stops after a minute or so after start-up and then runs fine. My ac stopped blowing cold yesterday, but is still blowing hard so it isn't the fan. I don't know if they are one problem or two... The sound started about 9 days before the ac stopped being cold. Getting the freon checked tomorrow.

SOURCE: Windshield wiper arm on passenger side won't move.

tighten the nut under the cap, of the wiper

SOURCE: Air conditioning fan makes loud noise the faster you ru it.

Concerning your broken vent -- this can be caused by a broken linkage or a malfunctioning servo motor as well. these vent have air ducts the sway back and forth to adjust the dual air flow function. if the servo o linkages are malfunctioning or not connected for some reason, it will not allow total control of the air flow and temperature range. Now, if you have a combination of a flow error and temperature error as well, thai can be caused by a combination of the two.

In this case, you will need to inspect the linkages as well as the servo motor function as well. in addition, i would test the air temp sensors for there operational value. they control the temp when you adjust the coll or hot function.

Concerning the Loud noise coming from the blower fan---

This issue can be caused by a misalignment within the blower housing or, it can also be caused by some minor damage within the motor itself, causing it to rotate in a erratic manner, in return, forcing it to rub against the housing itself. the best solution here is to extract this blower fan housing and inspect for lose fan propeller and motor stability. replace parts accordingly.

PLease rate and have a great day:)

Ned C Cook

• 3433 Answers
• Posted on May 30, 2009

SOURCE: 1999 yukon denali no ac or heat blowing

chk the fan speed resistors mounted in the fan housing. You should be able to see the wires going into the box with 2 screws holding the resistors in place. Good Luck.

SOURCE: After approx 40 min of highway driving the AC stops blowing cold

This is a problem solved by moderation. There are pressure switches in the system which cut off the compressor for too high a charge and too low a charge. The unit is suppose to cycle between a predetermined range, a moderation between high and low. If you were having problems before replacing the freon there is at least 1 pressure switch that could have been your problem in the beginning. If you have a manifold guage which shows high and low pressure you can tell when the pressure switch is open or closed. Some switches and for sure the autoparts store selling them can tell you the op[erating range of your switch. You can try just replacing the low pressure switch and fly blind without the manifold guages. Know how many ounces of Freon you put in? Compare to specs to see if you overcharged.

SOURCE: Car AC stopped blowing cold, compressor turns on, Freon at 45

check the thermo control amp, it is a sensor that keeps the evaporator from freezing. I had that problem on my 2000, it's a common nissan problem, google nissan ac problems.