I've got a 90 SC 5sp and a 97lx auto 4.6 both cars have low air flow coming from vents when ac is on heat works excellent on both but of course that's running on thr floor vents not dash. On the 97 I've pulled the dash (more than once) and repaired duct work which seems to help somewhat but air flow is still weak definitely cold air coming out on both just not enough of it.. Have not pulled thr dash in the 90 just wondering if anyone had any suggestions I'm thinking on the 97 maybe an evap core?
Inside air flow problems on 2 tibrds
- Thread starter 35th
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Good evening
Time to inspect and replaced HVAC hard vacuum hose/ lines. Most likely cracked. Very brittle due to age and heat cycles. No elasticity. Any leakage and or intermittent valve function has a drastic effect on HVAC operation. Use the EVTM as your guide.
Check the 2 hard vacuum hose/line from the check valve located on the driver side of the cowl/cover assembly under the windshield wiper motor. One branches off goes through the fire wall to the HVAC control unit.
The second vacuum hose/ line ends at the reservoir "ball" located under the passenger side splash shield/ fender.
The replacement vacuum hose/line size is DORMAN 47418 Tubing Dia.: 5/32". Get 6 feet.
Check valve is MOTORCRAFT YG337 {#D9AH19A563AA, D9AZ19A563AA}. One required. Highly suggest you replace it.
You will need vacuum connectors.
EDELMANN 765230 Connector - 1/8" Hose Size x 5/32" Hose Size.
EDELMANN 765220 Connector - 1/8" Hose Size x 5/32" Hose Size.
OR
DORMAN 47432 Soft Vacuum Tubing Connector Assortment.
OR
DORMAN 47430 1/8; 5/32; 3/16; 1/4 In. Soft Black Vacuum Tubing Connector Assortment.
Your discount stores should have them available. I order through Rock Auto.
In rare cases the HVAC control unit can be the cause. And yes I have had one fail after doing the above repairs on 1989 - 1993 Thunderbirds.
Time to inspect and replaced HVAC hard vacuum hose/ lines. Most likely cracked. Very brittle due to age and heat cycles. No elasticity. Any leakage and or intermittent valve function has a drastic effect on HVAC operation. Use the EVTM as your guide.
Check the 2 hard vacuum hose/line from the check valve located on the driver side of the cowl/cover assembly under the windshield wiper motor. One branches off goes through the fire wall to the HVAC control unit.
The second vacuum hose/ line ends at the reservoir "ball" located under the passenger side splash shield/ fender.
The replacement vacuum hose/line size is DORMAN 47418 Tubing Dia.: 5/32". Get 6 feet.
Check valve is MOTORCRAFT YG337 {#D9AH19A563AA, D9AZ19A563AA}. One required. Highly suggest you replace it.
You will need vacuum connectors.
EDELMANN 765230 Connector - 1/8" Hose Size x 5/32" Hose Size.
EDELMANN 765220 Connector - 1/8" Hose Size x 5/32" Hose Size.
OR
DORMAN 47432 Soft Vacuum Tubing Connector Assortment.
OR
DORMAN 47430 1/8; 5/32; 3/16; 1/4 In. Soft Black Vacuum Tubing Connector Assortment.
Your discount stores should have them available. I order through Rock Auto.
In rare cases the HVAC control unit can be the cause. And yes I have had one fail after doing the above repairs on 1989 - 1993 Thunderbirds.
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Not a vacumm issue at least not on the 97 could be on the 90 just starting on that one but I've already checked the lines on the 97 even went as far as making a temporary manual blend door lever and partially putting the dash back in and even though I could manually move the blend door it didn't increase air flow
Alright pulled the dash and airbox had to make a door to remove evap core got it reinstalled and sealed and magicly no change in air flow even thought evap was definitely filthy all vacuum hoses connections duct work doors in good shape but for the life of me I can't figure out why the air flow is so weak on high speed its as if you have it turned on the 2nd highest speed even though you can clearly hear the blower change speeds... The only thing I did notice although not sure why is it doesn't seem to draw in much air meaning if it's not drawing air in it can't blow it out but unsure why.
Have you considered using an inspection camera you can snake in from both the inlet and outlet(s) to witness the conditions inside those channels?
I have a handheld with a 3ft. long lead, and another that works w/my phone that is 10ft. I believe AutoZone has one in their tool rental inventory if you don't have one already. I use them on my SC all the time
Just seems odd you'd have the same issue w/more than one car - you don't have an irate x that thinks sugar in the gas tank is funny, do you...
Ken
I have a handheld with a 3ft. long lead, and another that works w/my phone that is 10ft. I believe AutoZone has one in their tool rental inventory if you don't have one already. I use them on my SC all the time
Just seems odd you'd have the same issue w/more than one car - you don't have an irate x that thinks sugar in the gas tank is funny, do you...
Ken
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On it irate x... That's funny but no sir same wife for years whom is awesome I did figure out on the 97 (hers) that the dash and air box where not properly aligned and the vents to duct work didn't have enough gasket left redid dash alignment and gasket weather strip where the vents seat to the duct work large improvement haven't started on the SC yet it's less important as it only gets driven 2 days a week and usually just myself in it but the 97 totes my children so it's much much more important to be cool inside during out south Carolina summers of 105 heat index