Question about 2000 GMC New Sierra 1500

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I have a 99 gmc truck and the a/c cuts off while driving down the road, replace control head, high pressure switch and low pressure switch and the a/c compressor relay any suggestions

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Did you change the orfice tube,it should be found somewhere in the front around the radiator.It may be clogged.Do you live in hot climate,then change it for sure.

Posted on Jul 23, 2009


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I was told by A/C guy I have a short somewhere to the high pressure switch. something is not kicking on the compressor. another mechanic said I need a new computer. what do you think

go with the ac guy
there are systems that prevent the ac compressor working
high pressure switch which cuts the ac clutch if the head pressure goes too high
low pressure switch which cuts power to the ac compressor if there
is no gas in the system
climate control systems which cut power when the ac is not required
fuses to the ac system
get a better explanation or seek advice from other ac mechanics

May 01, 2015 | Cars & Trucks

1 Answer

Where is the blower motor switch located

On some vehicles the switch is called the blower motor resistor. There is some confusion about whether you are missing fan speed or the A/C chilling the air.

For the chilling part, this is controlled by 2 pressure sensors in the system called a low pressure switch and a high pressure switch. The rpm of the engine can affect when stuff begins to work and when it cuts out. There is a correct amount of Freon needed for every system. The engine rpm contributes to the available amount of pressure in the Freon system. This is why some things are different from start-up to when the car is moving.

You need to do a pressure check for the Freon in the system. This can help indicate if a pressure switch is cutting off cooling power. For the fan speed, it is the blower motor resistor, a troublesome switch that has lagged behind technical improvements.

So you have 2 answers-1 for fan speed and the other about cooling functions. You can fix either separately as half the system can be good and the bad half is stopping all of it from cooling the car. Hope this helps

Feb 23, 2018 | 1996 Ford Thunderbird LX

1 Answer

My ac cabbot run on high speed, it will cool sometimes i have to keep turning switch off and on. what causes this?

if cut off in low pressure switch add gas, and if cut in high pressure switch reduce gas or replace orifice tube vaccum the system and recharge gas

Jul 01, 2011 | 1994 GMC Safari

1 Answer

2004 GMC Sierra 1500 5.3L(T). When driving down the road the AC goes from cold to hot all by itself. I touch nothing. I can move the controls later and nothing changes. Turn the truck off, turn the...


Aug 08, 2010 | 2003 Chevrolet Silverado 1500

1 Answer

Loss of power on 1998 ford powerstroke 7.3 . pcm threw a p1211 code went to ford and got new icp. already replaced ipr. the hpop is full of oil. it idles all day and can hold 3000 rpms just fine but...

Generally the computer is reading a problem with the fuel pressure being to high or to low. The ICP is one problem it could be and you changed it. The other could be Fuel pressure regulator control solenoid or problems with the injector (s).

Nov 25, 2009 | 1996 Ford F350 Crew Cab

1 Answer

99 GMC Jimmy cutting off while going down the road.

check the fuel pressure, if that is ok, check the electronic egr valve. it can be removed and cleaned and replaced.

Sep 17, 2009 | 1999 GMC Jimmy

1 Answer

99 Suburban A/C Not working

The A/C pressue switch may be bad as well. Also the mode switch on the control head inside the vehicle. There are many other exsisting problems pertaining to a/c. I suggest a manual from Auto Zone for many faults can be noted especially wiring can be at fault

May 23, 2009 | 1999 GMC Suburban

3 Answers

Ford F150 front tires won't engage in 4 wheel drive

look on fire wall pass. side you will see 2 parts with vacume lines attached 99 percent of the time that is what went i had the same problem

Dec 15, 2008 | 1999 Ford F150 Regular Cab

2 Answers

A/C sporadic compressor. Bypassed high and low with paper clip. Pressures good has Freon. Clutch tests OK. Vehicle runs for maybe 10 min or some times 30 then A/C shuts down. Maybe A/C will fire up...

This is just a suggestion but you should check to see if you have a thermostatic control switch in your evaporator this could be the cause if the intermittent problem.The switch is actually used tokeep your ac from freezing up i believe.

Jul 24, 2008 | 1999 GMC Suburban

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