Burban Man
Newbie
Hey all,
Long time lurker very infrequent poster, I have searched this forum and others high and low and apologize in advance if there's an answer in another thread somewhere, if there is I couldn't find it.
Truck is a 1998 K2500 ECLB, originally a 454 truck but has a 6.0 swapped in. 4l80e, floor shift 4wd. Pretty cool truck, was really rough when I got it and I'm still ironing out little things as I go.
I'm not getting any heat from my vents. I was looking up at the blend door actuator under the dash and when I turn the knob it doesn't react. At first I believed it to be dead or that the blend door was stuck or broken, but then I did some testing and I believe it's working normally. I've got power on the brown wire, ground on the black wire. I jumped 12v from the brown wire to the light blue signal wire and i watched the actuator immediately roll over and had nice heat coming from the vents. Took away 12v and it went back to full cold. This tells me that the actuator responds to voltage on the signal wire, the gears inside are not stripped, and the blend door is not broken or stuck.
This is where it gets weird, I took the dash bezel off and pulled the HVAC module out, and testing at the light blue wire on the large flat connector on the right side I'm getting 2.6v no matter what position the temp knob is in. This is the signal wire from the module to the actuator and I'm assuming that it's supposed to output 0-2v ish in cold, up to 12v in full heat. Maybe it's 0-5v, I can't find any info on this on alldata or anywhere else. I have 4 or 5 spare HVAC modules from random junkyard trucks that I use for parts or as backups and have plugged all of them in with no change, still get 2.6v on the light blue wire no matter what position the temp knob is in.
So, either I'm completely misunderstanding how the HVAC module controls the blend door actuator, I'm misunderstanding how the blend door actuator works internally and it's actually bad even though I can force it to work correctly, or I have 5 HVAC modules and they all have failed in the exact same way and have a dead chip or something that controls the blend door output??? Any input is appreciated.
On another note, I just finished the engine swap in October and so far so good, truck has been super reliable and I've used it full time as a work truck. All factory gauges work, A/C works, 4wd works in hi and low. Can't complain too much, just wish I could have some heat
Long time lurker very infrequent poster, I have searched this forum and others high and low and apologize in advance if there's an answer in another thread somewhere, if there is I couldn't find it.
Truck is a 1998 K2500 ECLB, originally a 454 truck but has a 6.0 swapped in. 4l80e, floor shift 4wd. Pretty cool truck, was really rough when I got it and I'm still ironing out little things as I go.
I'm not getting any heat from my vents. I was looking up at the blend door actuator under the dash and when I turn the knob it doesn't react. At first I believed it to be dead or that the blend door was stuck or broken, but then I did some testing and I believe it's working normally. I've got power on the brown wire, ground on the black wire. I jumped 12v from the brown wire to the light blue signal wire and i watched the actuator immediately roll over and had nice heat coming from the vents. Took away 12v and it went back to full cold. This tells me that the actuator responds to voltage on the signal wire, the gears inside are not stripped, and the blend door is not broken or stuck.
This is where it gets weird, I took the dash bezel off and pulled the HVAC module out, and testing at the light blue wire on the large flat connector on the right side I'm getting 2.6v no matter what position the temp knob is in. This is the signal wire from the module to the actuator and I'm assuming that it's supposed to output 0-2v ish in cold, up to 12v in full heat. Maybe it's 0-5v, I can't find any info on this on alldata or anywhere else. I have 4 or 5 spare HVAC modules from random junkyard trucks that I use for parts or as backups and have plugged all of them in with no change, still get 2.6v on the light blue wire no matter what position the temp knob is in.
So, either I'm completely misunderstanding how the HVAC module controls the blend door actuator, I'm misunderstanding how the blend door actuator works internally and it's actually bad even though I can force it to work correctly, or I have 5 HVAC modules and they all have failed in the exact same way and have a dead chip or something that controls the blend door output??? Any input is appreciated.
On another note, I just finished the engine swap in October and so far so good, truck has been super reliable and I've used it full time as a work truck. All factory gauges work, A/C works, 4wd works in hi and low. Can't complain too much, just wish I could have some heat