The circuit for high speed involves the relay to be closed. On a 1995 Chevy Pickup it is located behind the glove compartment. The lower speeds use a fan resistor pack for the different speeds. The voltage supplied to the resistor pack is usually a 25 amp inside fuse. The high speed circuit is supplied by a constant 12 volts that turns on the fan when the relay is energized. The voltage for the high speed circuit comes from a fuse under the hood. Usually a 50 amp. If all fuses are good then there might be a fusable link in the wire somewhere.
First you must check the ISC motor ( idle speed control) operation. Its located by the throttle body. It controls idle and high idle speeds. Good luck
You can get a replacement part from your local NAPA store for about 12 bucks.. it is located on the heater box in the engine compartment on the passenger side. follow the wiring harness and you will find it.. I'm guessing, your fan only works on high ??
cheack the reisat switch for burns its atacched to the blower houseing under the dash or on fire wall under the hood
There are two answers to that question, depending on the situation: 1. If an electric motor (fan motor) has an internal wiring problem or faulty bearings it can result in an excessive current draw. 2. It takes a lot of energy to move air and depending on the size of the fan motor it may just be designed to move a lot of air and of course that would require a large motor. Pick whichever answer best fits your situation.
1. heat control linkage disconnected or broken or vacuum source problems(low vaccum source or broken vacuum lines) 2. heater unit doors stuck or non functioning heater door actuators
If the blower works on slower speeds only I would suspect the high speed blower motor relay (under the hood in the power distribution box) or the switch itself. The blower speed resistor is working if all the slower speeds work.
If you only have high speed I would blame the blower speed resister. If you have no speeds and the fuse is good, I would blame the blower motor or the switch.
If you have no blower speeds at all, first check the fuse. If the fuse is okay I would suspect the blower speed switch and its electrical plug has melted. If the switch checks okay I would suspect the blower motor is bad. If you have high speed only, I would replace the blower motor speed resistor. If you have all lower blower speeds but no high speed, replace the high speed relay.
When you beat the blower motor, you are probably shaking the blower resister. The resister is what controls the blower speeds and is probably bad or loose.
If the blower motor randomly and intermittenly quits and does not work, chances are good the blower motor itself is faulty, if the blower motor does not work on all fan speeds from low through high, it most likely needs a blower motor resistor.
Only for the high speed. The lower speeds are controlled with the use of a blower motor speed resistor.
Normally when some speeds work and others don't, the problem is a bad, Blower Motor Resistor Pack. You will find it somewhere near the blower motor.
It would have a high speed relay and it would be in the power distribution box under the hood. The blower speed resister is for the lower speeds only.
A bad heater blower motor resistor would effect one or more blower speeds other than high.
If all speeds do not work, suspect the fuse, the switch, the switch connector or the blower motor. If only high speed works, suspect the blower motor speed resistor. If low speeds work and not high, suspect the blower motor relay.
If it has only high speed, the blower motor resistor has to be replaced to get all speeds back.
Sounds like a bad blower motor resistor block.