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"Well earlier this week I was warming up the Bronco for work. I kicked the heater on high, when all the 6z LOTS of smoke filled the cabin of the truck. It smelled like burning leaves and really scared the crap out of me. I turned the truck off and opened the doors to air it out (I was about two seconds from calling the fire department), luckily it just smoked some leaves and didn't catch fire. I logged on here and searched.
This is old hat to alot of you veterans, but this is my third fsb and I never had this crap happen before. The problem is leaves and small twigs fall through the cowl vent and create a tender box in the hvac system. When the leaves build up on the resistor next to the blower motor, they can catch FIRE off the heat of the resistor. So here's a little how to that anyone can do:
First remove your blower motor, you'll need a 5/16 socket to loosen the four screws, and it will easily pop out.
Once the blower is out of the way, you'll be able to scoop/vacuum out all the debris. Reach your arm all the way down the inner fender to get all the crap out, just try to get your hand in every nook and cranny the leaves could've got into. Resistor pack is the red thing.
See pic @ fsb2.jpg Photo by foxbodyordeath | Photobucket
This is all the crap that came out of mine, more than I ever imagined was in there.
Pic @ fsb1.jpg Photo by foxbodyordeath | Photobucket
Next, use your 5/16 to remove the resistor so you can clean it real good
Re-install the resistor, and hook the two plugs back in..
Pic @ fsb2.jpg Photo by foxbodyordeath | Photobucket
Re-install the blower motor and your done!
Since I bought this * the a/c and heat barely came out the vents, now it blows good and strong
Insufficient Heat TSB 88-09-10 for 87-88 Bronco & F Series
Insufficient heat inside of vehicles equipped with or without air conditioning may be caused by the heater air baffle missing from the plenum chamber. The heater air baffle prevents cold air from leaking in around the heater core.
ACTION: To correct this, check to see if the heater air baffle is present. If the heater air baffle is not present, install a heater air baffle using the following service procedure.
1. Remove the heater core access cover to see if the heater air baffle is present. If missing proceed to Step 2.
NOTE: IF THE TEMPERATURE BLEND DOOR SHAFT CAN BE SEEN NEXT TO THE HEATER CORE, A HEATER AIR BAFFLE NEEDS TO BE INSTALLED.
2. Remove the heater core.
3. Remove the heater core face gasket.
4. Install the heater air baffle, (E7TZ-18D416-A) by inserting the pin on the bottom of the baffle into the lower surface of the plenum chamber.
5. Reinstall the heater core face gasket (or equivalent Frost King R930).
6. Reinstall the heater core.
7. Apply a bead of Ford Silicone Sealer, (D6AZ-19562-AA) around the heater core access cover.
8. Reinstall the heater core access cover.
PART NUMBER PART NAME;
E7TZ-18D416-A Heater Air Baffle
D6AZ-19562-AA Ford Clear Silicone Sealer
WARRANTY STATUS: Eligible Under Basic Warranty Coverage
OPERATION DESCRIPTION TIME
880910A Inspect only 0.3 Hr.
880910B Inspect and install heater air baffle 0.6 Hr.
If you need more info on this, ask for it.
Same for Lack of Heat, Temperature Blend Door Cam Spring Does Not Blend Door to Seat Properly TSB 92-4-13 for Vehicles Built Prior to 11/11/91, 92 Bronco & F Series & F-47
& Low or No Heat/Air Conditioning, High Effort to Turn Temperature Control Knob, Poor Temperature Modulation TSB 96-13-7 for 92-95 Bronco, F Series, F-47
More Heat in a 90; "...So the '87-'91 trucks with factory A/C have a recirculation door in their HVAC system, it's there to cut off outside air and keep running only in-cab air through the blower. It's vacuum controlled, and only cuts outside air when you put the control lever to "off" or "max A/C". I found on FSB board that the problem with this is when you have -10 ambient temperature with some -20 windchill, heating up that air good could be a challenge for a truck with an aging heater core or tired blower fan. Just to see how much of difference it actually makes I zip-tied my recirculation door closed, thus running inside air through the HVAC system all winter long - things got real warm real quick, noticeable improvement even when truck is stationary. For the warmer days tho I want the recirculation door open so I can get fresh air in the cab as I drive... So I devised and implemented a solution in my '90 truck - I zip tied the vacum pot closed which means I can get tons of heat in the winter even with some -20 degree temperature sand summer time i can snip it off! the '92-'96 trucks utilize the same recirculation door setup as the '87-'91, so it should be possible to do this mod to one of these truck as well..."
Source: by 90bronco at Maritime Off-Road
More Heat; "...the 87-91 trucks with factory A/C have a recirculation door in their HVAC system, it's there to cut off outside air and keep running only in-cab air through the blower. It's vacuum controlled, and only cuts outside air when you put the control lever to off or max A/C. The problem I see with this is when you have 15F ambient temperature with some -20 windchill, heating up that air good could be a challenge for a truck with an aging heater core or tired blower fan. Last year just to see how much of difference it actually makes I zip-tied my recirculation door closed, thus running inside air through the HVAC system all winter long - things got real warm real quick, noticeable improvement even when truck is stationary. For the warmer days tho I want the recirculation door open so I can get fresh air in the cab as I drive... So I devised and implemented a solution in my 90 truck - I now have a manually controlled recirculation door that I can open and close to my liking, which means I can get tons of heat in the winter even with some nasty ambient temperatures..."
Source: by M.L.S.C. at FSB
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.
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
Blower Motor Does Not Operate Properly
Check resistor assembly for continuity of coils and thermal limiter. Is resistor good?
Check blower motor fuse. BTW, if you would fill out your Bronco Info, we could narrow info down such as for NO OPERATION IN HIGH BLOWER SETTING
CHECK BLOWER SPEEDS LO AND MEDIUM
With engine running and blower on high, check system airflow in each function selector position to determine which position(s) have incorrect airflow. Refer to vacuum application chart for correct system airflow.
Check vacuum supply hose to be sure it is connected to both the engine manifold and vacuum check valve.
Heater Core Failure, Repeated TSB 01-15-06 for 85-96
ISSUE: The majority of repeat heater core leaks are due to high flow rate or use of poor quality coolant. However, electrolysis should also be checked, especially when repeat repairs have occurred.
ACTION: If the heater core is leaking, review the location of the leakage and check the condition of the coolant.
1. If leaks are found on the inlet (or outlet) tubes entering / exiting the heater core, it is most likely due to due to high flow rate. Replace the heater core and install a restrictor in the heater hose closest to the engine block, reference Workshop Manual, Section 412.
2. lf leaks are found in the body of the heater core itself, and they do not appear to be the result of physical damage like contact or puncture, check the coolant for possible electrolysis.
Testing For Electrolysis;
Check for voltage in the cooling system by touching the negative contact of a voltmeter to the battery ground or a known good ground and suspend the positive lead in the coolant, making sure it is in contact with the coolant, but not touching any metal part of the radiator or cooling system. Both AC and DC voltages must be checked. Vehicles normally have DC voltages; however, a faulty engine block heater or faulty diode in the alternator can produce AC voltages. It is understood that coolant is lost due to heater core failure but try to obtain a voltage reading on the old coolant in the engine block before addition or replacement. To keep more coolant from exiting the heater core, clamp off heater core lines and measure coolant in the engine block. Try not to
dilute the original coolant with new coolant during testing if possible.
1. Determine whether coolant condition is acceptable.
a. Remove both cables from the battery and ensure they do not contact each other or the vehicle.
b. Touch negative lead of DC voltmeter to engine ground and positive lead in the coolant.
NOTE: POSITIVE TEST PROBE IS IN THE COOLANT FOR TESTING.
c. Check the voltage in the cooling system. If less than or equal to 0.4 volts (VDC) OK, reconnect battery cables and proceed to Step 2.
d. lf greater than 0.4 V, flush cooling system thoroughly.
e. Recheck voltage less than or equal to 0.4 V.
f. Reconnect battery cables.
g. Refill the system with appropriate Motorcraft® engine coolant.
2. Check for loose or missing grounds at static conditions.
a. Turn off all accessories. Turn ignition on but do not start engine.
b. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.
c. Voltage less than or equal to 0.4 V on all grounds OK.
d. Any one greater than 0.4 V, check and clean ground cable connections.
e. Check accessories without using the on/off switch on the vehicle instrument panel; use a jumper wire to ground.
f. Plug in engine block heater, if equipped, and test.
g. Recheck voltage less than or equal to 0.4 V.
h. Unplug engine block heater, if equipped.
3. Check for loose, missing, or inadequate grounds.
a. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.
b. Crank engine but do not start.
c. Monitor voltage while cranking. Less than or equal to 0.4V OK
d. If greater than 0.4 V, ground or repair starter.
e. Start engine and run at about 2000 rpm.
f. Turn on all accessories including those customer only uses occasionally such as CB radio, cell phone, etc.
g. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.
h. Voltage less than or equal to 0.4 V OK
i. If greater than 0.4 V, turn off one item at a time until voltage drops to less than or equal to 0.4 V. Repair ground to the accessory just identified.
j. Recheck voltage less than or equal to 0.4 VDC
k. Turn the DVOM to AC volts.
l. Check for ANY AC voltage greater than 0.4.
m. If any AC voltage is present, try turning off each accessory one at a time including blower motor and any fan motors.
n. If AC voltage is still present, shut engine off and remove B+ from the alternator and tape it up, then retest.
o. If voltage drops gradually to less than or equal to 0.4 VAC, the ground straps may simply be overloaded by added accessories. Test by using a heavy gauge jumper to ground. If indicated, install heavier gauge ground strap(s) and recheck.
NOTE If vehicle is equipped with electric cooling fans, be sure they cycle during this testing and monitor voltage when they are on, and off.
CAUTION: DO NOT GROUND HEATER CORE. IF THE HEATER CORE IS GROUNDED, YOU HAVE PROVIDED THE ELECTROLYSIS A PATH THROUGH THE HEATER CORE. THIS WOULD CAUSE THE HEATER CORE TO BECOME AN ANODE OR RECEIVER AND IT WOULD PROMOTE THE ELECTROLYSIS, OR ANY STRAY VOLTAGE TO USE THE COOLANT AS THE GROUND PATH.
4. Refill the engine cooling system, reference Workshop Manual, Section 303-03.
NOTE IF THE HEAT OUTPUT IS INSUFFICIENT, OR IF THE ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURES, VERIFY PROPER THERMOSTAT OPERATION AND REPEAT
PROCEDURE IF REQUIRED.
WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage. by Ford via me.