HDJ81 windows fogging (1 Viewer)

[torqueluvr]

Read some stuff about the gasser 80s, but wanted to consult the diesel guru's too.

1992 HDJ81, the car will not de fog any of the windows, and half the windshield. Living in Vancouver, Canada we get very very moist air for about 6-7 months of the year. One thing I noticed is my AC hasn't worked sinced I've owned it (last November) which I know will make a difference. The other interesting thing is that my re-circ and fresh air switch on the climate control seems to be stuck on fresh air, no matter what setting it is on - vent, defrost etc. Maybe something in the climate control? Maybe something in the air flaps?

What do you guys think? Before I drop $350 to get the AC serviced.

 

[IanB]

So it still directs air to the vents at the base of the windshield, just doesn't get rid of the fogging? Fixing the AC will help a great deal, removes the moisture from the air you're blowing at the windshield, so either way I'd get that working. As for the fresh air/recirc function, that's switched with the button on the HVAC, it doesn't change on its own depending on vent mode if that's what you're asking.

If the vent modes send the air to the vents they are supposed to, and you're getting heat from the vents when you've got the heat turned up, then I'd be looking at the AC as the issue.

 

[MonsterCruiser]

Should be no problem to defog even if you remove the A/C. I suspect that even though your climate control says it's stuck on "fresh" air, the flaps are probably stuck in the recirc position. This will definitely cause you to fog up and have difficulty de-fogging and probably impossible to totally de-fog.

I don't know how difficult it is to access the flaps. Do you just pull the cowl off at the base of the windscreen?

 

[Douglas S]

I tend not to use the AC to defog and I've never noticed a problem. Could be a lot of things: clogged heater core, weak fan, stuck flaps. The problems that occur in gas trucks should be the same ones that occur in a diesel.

 

[tweeek]

Interesting, I find the opposite as above. Defogging in mine is almost impossible without the ac compressor running. If compressor is running, there is no issues.

 

[Greg_B]

There is the Vancouver Is and Lower Mainland versus the rest of Canada in this equation I think. I was reminded of that this winter when driving from Abbotsford to Yellowknife, via Kelowna, Calgary and Fort Mac in the 80. I was commenting to folk on the trip that I could not get my windows to not ice up on the inside in the cold dry climate. I was asked...have outside air open, or on recirc. My set mode in the Lower Mainland is AC on and set to recirc; Having recirc on with the AC drying the air works wonders in the damp months. Not so much in the dry cold. I turned the AC off (so dry no need to dry the air) and switched from recirc to outside air. Was much better.

As someone else said, could be a few things. The two I would make sure are working are AC and check if the flapper is getting moved, via a little servo motor. Have to remove some of the dash to access the servo which is on the top. Been a while since I've been in there and if I recall more I will post up.

My daily this winter has been the BJ74. With no working AC. I wiped down all the inside glass with anti-fog and drive around on the real wet days with at least one window open so there is air movement. Even with my heater on high and set to defrost.

hth's
gb

 

[tweeek]

There is the Vancouver Is and Lower Mainland versus the rest of Canada in this equation I think. I was reminded of that this winter when driving from Abbotsford to Yellowknife, via Kelowna, Calgary and Fort Mac in the 80. I was commenting to folk on the trip that I could not get my windows to not ice up on the inside in the cold dry climate. I was asked...have outside air open, or on recirc. My set mode in the Lower Mainland is AC on and set to recirc; Having recirc on with the AC drying the air works wonders in the damp months. Not so much in the dry cold. I turned the AC off (so dry no need to dry the air) and switched from recirc to outside air. Was much better.

As someone else said, could be a few things. The two I would make sure are working are AC and check if the flapper is getting moved, via a little servo motor. Have to remove some of the dash to access the servo which is on the top. Been a while since I've been in there and if I recall more I will post up.

My daily this winter has been the BJ74. With no working AC. I wiped down all the inside glass with anti-fog and drive around on the real wet days with at least one window open so there is air movement. Even with my heater on high and set to defrost.

hth's
gb

That makes good sense, I'm on the wet coast ad well.

Since OP is on lower mainland, some AC work is probably a good bet.

 

[Greg_B]

Correction on the flaps: remove your glovebox and you'll be able to see if the inside/outside flap is moving. The heater core valve and defrost/foot/middle vent controls are accessed by getting into the dash. Sounds like you just need to check the inside/outside one behind your glovebox though, as a start. Then look to your AC.

hth's
gb

 

[torqueluvr]

So I looked a little more into this. After some careful examining, my recirc and fresh air button does, in fact, work, but the light on the dash doesn't change. I can tell by putting the fan on HI, then pressing the recirc/fresh button. When I do so I can hear a definite change in fan noise, and I'm pretty sure that's when it goes into recirc mode. In my experience with other vehicles, whenever I put it on recirc its like a door closes and the fan has to push against a blend door or something and the fan noise is always louder. No fog inside the truck today, and it was just as wet as yesterday. Thanks everyone. I'll be sure to get the AC fixed, and that will help too.

 

[IanB]

You should be able to replace the burnt out bulb in the HVAC if you were so inclined.