I REMOVED THE AC FAN SWITCH FOR THE THE FAN AND WHEN I PUT IT BACK ON IT DOES NOT TURN ON ANY MORE. HOW DO I RE-INSTALL THIS TO WORK AND TURN ON FAN FOR AC AND HEATER?

You may have a bad relay on the fan switch or the temp sensor is bad. Not reading the temp. Fan is activated by temperature reaching a set level. It is also set up to turn on when you turn on the AC or defrost.
If the fan is working for AC, then you have a bad senser or reley

NO
there should be a separate fan in front of the condenser that will come on
If you do not have a separate fan then the cooling fan may be in the circuit to work when the ac is on as you need an air flow through the condenser to remove the heat from the compressed gas to turn it back to a liquid and a normal coolant fan will only work when the coolant sensor tells the ECM to switch it on
best talk with an accredited ac speciaist shop to find out what you have

The easiest way to tell if the fans work is to put your AC on max, even if it does not work, both your fans should turn on as long as the vehicle is running. if they do not turn on, check the fuses first, then the fan relays, you can usually swap the horn relay to see if they come on, if you still do not see the fans working, they may need to be replaced, the thermal switch is bypassed while the AC is on max so if the fans come on then, but not when engine gets hot, it may require replacement,
note: if both fans work during ac max operation all the fuses and relays in there circuit are working and need no attention

If the fans work, (I'm guessing there are two of them) only when the A/C is on, then it means that the temperature sensor is damage. If possible, have a professional take a look at it. Both fans are OK,

Normally the ac fan (in front of the condenser) will run as soon as the ac is switched on. This condenser gets hot when the gas is being compressed and needs to have the heat removed for the system to work IT will switch on regardless of the ambient temperature as it is connected directly to the ac compressor clutch. IF you are referring to the heater fan inside then it will only work with the heater fan on or with both ac and heater on but will not always work with just the ac on.

It may not be a control unit issue. Be sure to check all fuses. You may have a pressure switch issue. There are at least 2 pressure switches located in the engine compartment. One is usually located on the back of the ac pump and there is usually one on the passenger side near the firewall on one of the aluminum ac lines. You can simply unplug the one by the firewall and take a paper clip and unfold it and use it for a jumper on the connector. Put one end of the clip in one side of the connector (the end of the connector that plugs into the switch) and the other end of the clip into the other side of the connector. Start your Tahoe and turn the ac on and if the ac pump is turning with the ac clutch engaged that means that you either have a bad switch or your are low on refrigerant. Feel the aluminum ac lines and see if they are getting cold. If so I would suspect a bad pressure switch. You can remove the paper clip while the vehicle is running and put it back in if you are not sure if the ac clutch is engaged. It should make a clicking noise when it engages and disengages. It is very simple to replace that switch. Simply unscrew it and screw the new one in and plug it in. It will hiss just a little when you remove and install so be quick. It will stop when you remove the old one and will hiss again a little when installing the new one. The switch on the back of the pump is not so easy. The refrigerant needs to be evacuated from the system before it can be replaced.

Hi!!
When the Blower Motor Resistor (controls blower speeds) goes bad, the blower motor works only on HIGH SPEED. REPLACE IT.
BLOWER MOTOR RESISTOR Removal & Installation

• Disconnect negative battery cable.
• Remove right lower instrument panel insulator panel.
• Disconnect blower resistor connector located behind right side of dash.
• Remove blower resistor screws and blower resistor.

To install, reverse removal procedure
Good Luck!! A HELPFUL - 4 THUMBS - rating for this solution would be greatly appreciated. Thank you for using FixYa!!

you might check your switch sounds like to me that your two lower speed sides of the switch maybe burnwed out.

temperature switch bad goto dealer parts get diagram(they give free)find switch remove plug to switch (turn ignition key to on position)take short piece of wire jump plug wires see if fan starts if not check fan motors for operation if they do switch bad replace you can get better deal at local parts house than dealer on switch try that see if thats whats doing it!!!!Best Of Luck toYou!!!!

Look at the fan radiator switch
Try unplug the CTS,if you see the radiator working continuously
Than the CTS, than change it