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Just purchased the truck with a 5 year old new “working” AC to find out the system was empty, leaking, and needed a new compressor. So I had everything replaced (a new York compressor) and charged it. It blows cold but it’s very weak there is no difference in the fan speeds between low and high it’s all just weak. I’ve searched all the forums and cannot find a similar issue to help troubleshoot. The vehicle has factory AC and heat.
Where should I look first? Someone said connect blower motor to direct 12V to see if it blows hard but I am not sure where the connections would be. Another video said it could be in the dash unit, possible something disconnected behind there super easy fix?
How are the heat and vent settings working for blower output?
Could be a bad blower, or connection, or switch, or blower resistor group, or could be a non opening door ... but first look under the passenger side over feet area, push that door up "open", any "varmit home supplies" in the evaporator core fins blocking it? Also could be cowl vent bowls trashed up, several threads on cleaning those out.
How are the heat and vent settings working for blower output?
Could be a bad blower, or connection, or switch, or blower resistor group, or could be a non opening door ... but first look under the passenger side over feet area, push that door up "open", any "varmit home supplies" in the evaporator core fins blocking it? Also could be cowl vent bowls trashed up, several threads on cleaning those out.
The heat is the same speed as the AC only one speed and it’s low speed which makes me think it isn’t the resistor since it is low speed and not high speed. The door underneath the dash opens and closes fine and there doesn’t appear to be any trash in there. The heating unit inside appears to be new. I looked up in the passenger side cowl and there wasn’t much in there a couple pineneedles I got out and I hit it with compressed air and it did not blow anything crazy out so I think the cowls are clean.
What connections should I check to make sure they are good. Or can I run through it with a voltometer?
What connections should I check to make sure they are good. Or can I run through it with a voltometer?
Look inthis thread, down at post #6. ... for good diagrams. Gently wiggle a few wires near connectors with fan on hi. The blower resistor is a group but if the blower doesn't run better on hi, which bypasses lower speed or resistors, then likely not the resistor pack. Don't ignore the switch either.
Switch is 19986.
I've had switches them selves fail under the high electrical load of high speed on a couple cars before, just the switch contacts burnt, etc. Was not the resistor that failed in those. I've replaced the blower motor itself in my '95 Thunderbird as it died, and I had to wire a fused jumper to run the blower in our '01 Mercury in a cold winter '02 to get heat while waiting for my local dealer to get a new resistor in under warranty (they diagnosed it, ordered the part, but we had a trip to take).
Ok update... I pulled out the dash unit. The back of the switch looks to be in pretty bad shape, the wire is pretty black towards the metal connector. There are 4 posts and only a single orange wire connected to the closest top post (see attached pics). I can't find any diagrams but I am assuming there should be a 3 or 4 plug connector attached to this and not just a single wire.
I am hoping this is the issue with my system having a single slow speed. Please help me troubleshoot further. Questions:
1. Is there another wire harness/plug behind the dash that should be connected to this switch?
2. Is there a way to check the switch for functionality with a voltmeter?
3. Is there an easy way to bypass the switch to make sure the blower motor spins faster?
4. How do you remove the switch to replace it? Can't find any help onlye
5. What is the part number for the replacement switch. factory ac and heat
Last edited by Deadbuck; Mar 17, 2024 at 07:24 PM.
Reason: added picture
If you remove the resistor from the ducting (or just unplug it from the harness), the fan will only blow at full speed regardless of the speed you set the switch on the dash. You can use that as a temp work around if you're needing to source parts, etc.
Ignor the yellow marking. At the bottom of the drawing is the plug that goes on the switch. You can remove the dash trim and then pull the heat / ac control section out towards you. You'll need to pull the headlight **** loose (button on top behind dash) and the wiper **** (tab).
Below is the switch to blower wiring ... not sure what you'll find after these years.
1. Is there another wire harness/plug behind the dash that should be connected to this switch? AFAIK NO only one elec connector. 2. Is there a way to check the switch for functionality with a voltmeter? It is a step switch, so I believe it should multimeter (ohm out ?) test and show a increase with each setting?? 3. Is there an easy way to bypass the switch to make sure the blower motor spins faster? Not sure, but by passing a switch is a great way to test a fuse function. 4. How do you remove the switch to replace it? Can't find any help on line. Once you get the instrumental panel trim bezel off, the switch itself is held in place with a couple of screws. That you can access by removing the complete environmental panel. I'd take the radio out 1st. 5. What is the part number for the replacement switch factory ac and heat.. Part #: D5AZ-19986-A
1. Is there another wire harness/plug behind the dash that should be connected to this switch? AFAIK NO only one elec connector. 2. Is there a way to check the switch for functionality with a voltmeter? It is a step switch, so I believe it should multimeter (ohm out ?) test and show a increase with each setting?? 3. Is there an easy way to bypass the switch to make sure the blower motor spins faster? Not sure, but by passing a switch is a great way to test a fuse function. 4. How do you remove the switch to replace it? Can't find any help on line. Once you get the instrumental panel trim bezel off, the switch itself is held in place with a couple of screws. That you can access by removing the complete environmental panel. I'd take the radio out 1st. 5. What is the part number for the replacement switch factory ac and heat.. Part #: D5AZ-19986-A
OK, I got the issue fixed! On the AC switch there was only the orange wire connected. I remove the instrument cluster and way in the back there was a plug for the AC switch that was cut and hacked up for some reason. I got it fixed and plugged it in and now I have four range of power with the functioning switch. All is good. Thanks for everybody’s help.
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I've replaced the blower motor itself in my '95 Thunderbird as it died, and I had to wire a fused jumper to run the blower in our '01 Mercury in a cold winter '02 to get heat while waiting for my local dealer to get a new resistor in under warranty (they diagnosed it, ordered the part, but we had a trip to take).
