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Ignition key gremlins and HVAC

Tim_with_the_tj

TJ Enthusiast
Joined
Jul 25, 2021
Messages
240
Location
Vancouver, WA
I've read a bunch of threads and watched a couple videos about the ignition lock cylinder, actuator mechanism, and ignition switch. I'm not sure where my exact problem is, but here is what's going on.

1997 TJ SE model.

My HVAC fan does not blow at all sometimes, and other times it works fine. Today I discovered if I wiggle the key with the Jeep running, the HVAC fan will suddenly come on or go off. I only have one key for the Jeep and it's very worn. I'm sure it's an original key from it's 1996 production. The Jeep runs fine. It never cuts out when wiggling the key, and the key cannot be removed while in the run position.

What's causing the HVAC fan problem?

Lock cylinder or key too worn?
Actuator pin worn?
Ignition switch faulty?

I'm assuming one of the above parts is the culprit. I mostly understand how those work together, but unsure on whether a worn key and worn lock cylinder tumblers can cause this.

To recap: Jeep starts up every time and runs with no issues. The only thing glitching is the HVAC fan. Wiggle the key while the Jeep is running and the fan starts working/stops working. Nothing else seems to be affected by wiggling the key.

Possibly relevant info: The airbag light intermittently comes on. I don't have a rear defrost. My turn signals work. My wipers work.

Thanks for any help. I should go take the thing apart and look at it later.
 

WestCoastDan

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Joined
Sep 2, 2021
Messages
505
Location
SoCal
The key switch was causing similar issues on the radio power in our '03.
Pretty easy swap but be sure to check what hardware is holding yours to the column; I was lucky enough to have the right Torx bit in my toolbox.
 
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Tim_with_the_tj

Tim_with_the_tj

TJ Enthusiast
Joined
Jul 25, 2021
Messages
240
Location
Vancouver, WA
581B6B52-4BA5-4E04-9812-52FDB1500481.jpeg

Here’s the well-used key for reference.
 

SonOfAnakin

Member
Joined
Nov 2, 2021
Messages
26
Location
Ann Arbor, MI
I just replaced mine switch for the same reason. Didn’t help. If I wiggle the key everything comes back on. Will probably replace the actuator and cylinder next just to take care of it. But want all new locks to match. Looking for a set I can buy all together.
 
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Tim_with_the_tj

Tim_with_the_tj

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Jul 25, 2021
Messages
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Vancouver, WA
No, not the lock cylinder, the actual electrical switch that the lock cylinder turns to engage the starter and ign circuits.
View attachment 288380
I just replaced mine switch for the same reason. Didn’t help. If I wiggle the key everything comes back on. Will probably replace the actuator and cylinder next just to take care of it. But want all new locks to match. Looking for a set I can buy all together.
You should also inspect the ignition switch wiring harness connectors and wires for signs of overheating...
This can cause intermittent problems with power to accessories.
Thanks, guys. I will report back after I have time to disassemble and take a look.
 

Mavesar

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Supporting Member
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Nov 5, 2021
Messages
37
Location
Ridgecrest, CA
I have the same problem on my 01 TJ was going to replace the fan and resistor as a set, since it started about a month after I replaced the resistor (same time it started only working on high). all the switched power from the key looks good. If I jiggle the key it does start working. All the wiring looks good. Finishing up gears today - hopefully - and will be doing the fan/resistor next will report back on if it works or not.
 
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Tim_with_the_tj

Tim_with_the_tj

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Jul 25, 2021
Messages
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Vancouver, WA
I have the same problem on my 01 TJ was going to replace the fan and resistor as a set, since it started about a month after I replaced the resistor (same time it started only working on high). all the switched power from the key looks good. If I jiggle the key it does start working. All the wiring looks good. Finishing up gears today - hopefully - and will be doing the fan/resistor next will report back on if it works or not.
I would think if jiggling the ignition key makes a change to the HVAC fan working or not (like mine) then therein lies the problem... somewhere at the key. It's interesting you said all the switched power from the key looks good. Where are you testing the wiring? Did you test the switched power while jiggling the key? Might need two people for that.

Congrats on the gears. That usually makes a big difference.
 

Mavesar

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I pulled apart the ignition and tested the output of the ignition module on a bench. What is happening with mine is I have to move the key close to start position where it clicks but not fare enough to start it disables the accessories for a sec. sometimes just once sometimes up to 3 times to get it to start working. no other accessories are having problems stereo, switch power accessories all work it is just HVAC fan that doesn't start so I am starting with HVAC.
 

WestCoastDan

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Sep 2, 2021
Messages
505
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SoCal
I pulled apart the ignition and tested the output of the ignition module on a bench. What is happening with mine is I have to move the key close to start position where it clicks but not fare enough to start it disables the accessories for a sec. sometimes just once sometimes up to 3 times to get it to start working. no other accessories are having problems stereo, switch power accessories all work it is just HVAC fan that doesn't start so I am starting with HVAC.
The ignition switch is a tricky piece, and it only cost about $20.
I'd start there as this is exactly what was happening to my stereo; intermittent shutting down and/or not functioning at all upon startup.
 
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Mavesar

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Ridgecrest, CA
The ignition switch is a tricky piece, and it only cost about $20.
I'd start there as this is exactly what was happening to my stereo; intermittent shutting down and/or not functioning at all upon startup.
If my stereo was intermittent like yours I would start with the module too. Everything else other then the HVAC fan works like it should on mine. Only the blower fan is acting up, I can even hear the A/C cycling. It is possible it is a relay that is failing in the fan circuit but since my fan only works on Hi speed I am assuming my resistor is smoked and since I put it in and it only lasted a month I am guessing that my blower fan is pulling to many amps and smoked the new mopar resistor. so replacing both resistor and blower to see if it solves the issues. if it is the fan I am just glad it didn't smoke the wiring as it is failing.
 
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Tim_with_the_tj

Tim_with_the_tj

TJ Enthusiast
Joined
Jul 25, 2021
Messages
240
Location
Vancouver, WA
I pulled apart the ignition and tested the output of the ignition module on a bench. What is happening with mine is I have to move the key close to start position where it clicks but not fare enough to start it disables the accessories for a sec. sometimes just once sometimes up to 3 times to get it to start working. no other accessories are having problems stereo, switch power accessories all work it is just HVAC fan that doesn't start so I am starting with HVAC.
You just described exactly how mine reacts when the key is moved. Sounds like we have the same problem, whatever it is.
 
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Tim_with_the_tj

Tim_with_the_tj

TJ Enthusiast
Joined
Jul 25, 2021
Messages
240
Location
Vancouver, WA
If my stereo was intermittent like yours I would start with the module too. Everything else other then the HVAC fan works like it should on mine. Only the blower fan is acting up, I can even hear the A/C cycling. It is possible it is a relay that is failing in the fan circuit but since my fan only works on Hi speed I am assuming my resistor is smoked and since I put it in and it only lasted a month I am guessing that my blower fan is pulling to many amps and smoked the new mopar resistor. so replacing both resistor and blower to see if it solves the issues. if it is the fan I am just glad it didn't smoke the wiring as it is failing.
...except for the fan only working on high. My fan works on all speeds (if you have the key in just the right position).
 

Mavesar

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Nov 5, 2021
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Ridgecrest, CA
You just described exactly how mine reacts when the key is moved. Sounds like we have the same problem, whatever it is.
Hopefully. I have a mopar blower and resistor and will replace them this weekend I will let you know if it fixes it. My key was worn out badly too so I pulled the ignition cylinder and had a locksmith replace the plates and cut some new keys based on the plate numbers he pulled out. This gave me new keys that still work on my doors and stopped the key falling out of the ignition :)
 
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Tim_with_the_tj

Tim_with_the_tj

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Joined
Jul 25, 2021
Messages
240
Location
Vancouver, WA
Hopefully. I have a mopar blower and resistor and will replace them this weekend I will let you know if it fixes it. My key was worn out badly too so I pulled the ignition cylinder and had a locksmith replace the plates and cut some new keys based on the plate numbers he pulled out. This gave me new keys that still work on my doors and stopped the key falling out of the ignition :)
Yeah, let me know if it works. Thanks.

I have considered doing the same to get new keys. How much did he charge you?
 

Mavesar

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Nov 5, 2021
Messages
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Location
Ridgecrest, CA
Yeah, let me know if it works. Thanks.

I have considered doing the same to get new keys. How much did he charge you?
he charged me $20.00. $3.00 for each key and $14.00 to replace plates in cylinder. I just took him the cylinder so no real labor it only takes 10 min to change out the plates.