96 bronco, Heat/ac works intermittently.

[scubscout53]

I can get in my truck and the heat/ac work fine, stop for gas or whatever, restart and nothing. Compressor is working, dryer is very cold, just no air coming through the vents. Fuses are all good. I suspect the issue is between the control panel and the blower. I removed the connection at the blower and reattached it and nothing. With the truck running I have played with the wires connected to all a/c components to see if it might have been a contact issue, still nothing. I haven't removed the dash panel but I'm about ready to. I've considered the compressor switch but the compressor is coming on and cycling.Any suggestions other than that?

 

[L\Bronco]

I can get in my truck and the heat/ac work fine, stop for gas or whatever, restart and nothing. Compressor is working, dryer is very cold, just no air coming through the vents. Fuses are all good. I suspect the issue is between the control panel and the blower. I removed the connection at the blower and reattached it and nothing. With the truck running I have played with the wires connected to all a/c components to see if it might have been a contact issue, still nothing. I haven't removed the dash panel but I'm about ready to. I've considered the compressor switch but the compressor is coming on and cycling.Any suggestions other than that?

Sounds like the blower\fan isn't working, correct? Does it work on any speed when it quits?
I would suggest a test light connected between the 2 terminals of the blower motor connector with the controls set to high speed and A/C.
Do this test when it isn't working. If the light lights, replace the blower motor, if not, report back for more help.
Have you mentioned the year?
Hope that helps
Cheers

 

[scubscout53]

Sounds like the blower\fan isn't working, correct? Does it work on any speed when it quits?
I would suggest a test light connected between the 2 terminals of the blower motor connector with the controls set to high speed and A/C.
Do this test when it isn't working. If the light lights, replace the blower motor, if not, report back for more help.
Have you mentioned the year?
Hope that helps
Cheers

Sounds like the blower\fan isn't working, correct? Does it work on any speed when it quits?
I would suggest a test light connected between the 2 terminals of the blower motor connector with the controls set to high speed and A/C.
Do this test when it isn't working. If the light lights, replace the blower motor, if not, report back for more help.
Have you mentioned the year?
Hope that helps
Cheers

96. If it is working it works at all speeds but it’s all or nothing meaning it either blows at all speeds or none.
I’ll try the test light and let you know. Thanks

 

[miesk5]

Yo subacute
Following from 1996 Bronco/F Series Workshop Manual (partial) @ http://www.diesel-dave.com/vehic/manual/stj/stjleft.htm
DIAGNOSIS AND TESTING

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Symptom Chart — Climate Control System​

CLIMATE CONTROL SYSTEM

Condition	Possible Source	Action
Insufficient, Erratic, or No Heat	Low radiator coolant due to coolant leaks.	CHECK radiator cap pressure. REPLACE if below minimum pressure. FILL to specified coolant level. PRESSURE TEST for engine cooling system and heating system leaks. SERVICE as required.
	Engine overheating.	REMOVE bugs, leaves, etc. from radiator and support or A/C condenser core fins. CHECK for: Operation of engine fan clutchLoose drive beltSticking thermostatIncorrect ignition timingWater pump impeller damageRestricted cooling system SERVICE as required.
	Loose drive belt.	REPLACE drive belt if cracked or worn and ADJUST drive belt tension.
	Thermostat.	FEEL heater water hoses. If the heater water hoses are too hot to hold, the thermostat is OK. If the heater water hoses do not get too hot to hold, REPLACE the thermostat. If only one heater water hose gets hot while the other remains cool, a plugged heater water hose or heater core is indicated.
	Heater water hoses.	CHECK condition and routing of hoses. GO to Pinpoint Test A.
Blower Motor Does Not Operate Properly	Blower motor.	GO to Pinpoint Test D, Pinpoint Test E and Pinpoint Test F to test for specific condition. See each Test @ http://www.diesel-dave.com/vehic/manual/stj/stjc0021.htm#d
Insufficient Cooling	Low refrigerant charge.	GO to Pinpoint Test C or Pinpoint Test G for specific condition.
No Switching Between Function Selections	Vacuum leak.	GO to Pinpoint Test B.

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[scubscout53]

Yo subacute
Following from 1996 Bronco/F Series Workshop Manual (partial) @ http://www.diesel-dave.com/vehic/manual/stj/stjleft.htm
DIAGNOSIS AND TESTING

---

Symptom Chart — Climate Control System​

CLIMATE CONTROL SYSTEM

Condition	Possible Source	Action
Insufficient, Erratic, or No Heat	Low radiator coolant due to coolant leaks.	CHECK radiator cap pressure. REPLACE if below minimum pressure. FILL to specified coolant level. PRESSURE TEST for engine cooling system and heating system leaks. SERVICE as required.
	Engine overheating.	REMOVE bugs, leaves, etc. from radiator and support or A/C condenser core fins. CHECK for: Operation of engine fan clutchLoose drive beltSticking thermostatIncorrect ignition timingWater pump impeller damageRestricted cooling system SERVICE as required.
	Loose drive belt.	REPLACE drive belt if cracked or worn and ADJUST drive belt tension.
	Thermostat.	FEEL heater water hoses. If the heater water hoses are too hot to hold, the thermostat is OK. If the heater water hoses do not get too hot to hold, REPLACE the thermostat. If only one heater water hose gets hot while the other remains cool, a plugged heater water hose or heater core is indicated.
	Heater water hoses.	CHECK condition and routing of hoses. GO to Pinpoint Test A.
Blower Motor Does Not Operate Properly	Blower motor.	GO to Pinpoint Test D, Pinpoint Test E and Pinpoint Test F to test for specific condition. See each Test @ http://www.diesel-dave.com/vehic/manual/stj/stjc0021.htm#d
Insufficient Cooling	Low refrigerant charge.	GO to Pinpoint Test C or Pinpoint Test G for specific condition.
No Switching Between Function Selections	Vacuum leak.	GO to Pinpoint Test B.

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How do I find specific circuits quickly? For example it says check circuit 249 but I don't see this in the diagrams. Is there a way of downloading the workshop manual and not have to jump around and have so many pages open?

 

[wyo58]

Years ago i had a blower that worked basically whenever it wanted to. Tracked it down to the motor and replaced it no problems from there on. I got curious and wanted to see inside the old motor, found that the brushes were so worn out that they barely were touching the armature. Once in a while they would bounce around and touch it and run, food for thought.

 

[scubscout53]

Makes sense.I've started on the a/c control panel and going to try to eliminate that. Blower will be my next move.

 

[L\Bronco]

Makes sense.I've started on the a/c control panel and going to try to eliminate that. Blower will be my next move.

Watch for a melted plug on the blower speed switch. Its pretty common

 

[Tiha]

When it is NOT working, pop the hood and hit the blower motor, tap on it with a hammer.

If it comes on, you need a new blower motor.

 

[scubscout53]

Well guess what...after tapping with a hammer it started blowing. Looks like I'll be replacing the blower motor

 

[L\Bronco]

When it is NOT working, pop the hood and hit the blower motor, tap on it with a hammer.

If it comes on, you need a new blower motor.

Good call Tiha!
Often the common sense approach is the best one!

 

[Motech]

When it is NOT working, pop the hood and hit the blower motor, tap on it with a hammer.

If it comes on, you need a new blower motor.

I love the old-school, tried-n-true hammer diagnostic technique.

I confess I've never used the "whack" test on a blower motor. Have and still do use it on relays, fuel pumps (whack the tank), starters. IAC valves, ECMs, etc.

Nice!