Defroster workaround
2008 Allegro Freightliner FRED …. My defroster has quit working. Very little air flow. I’ve taken it apart as far as I’m comfortable with. Cleaned the hoses from the junction box. Additionally the...
Forum Discussion
Have you verified the AC system 12 volt VACUMM PUMP is functioning and pulling a vacuum?. ALL Diesels require a 12 volt vacuum pump. This pump supplies the vacuum needed to operate the Dash AC/Heater blend doors. Also, the normal result of NO vacumm is default to defroster ducts. But, you year might be different and requires vacumm to move the doors. Doug
PS, this pump is located on the outside firewall and easy to see. They usually look like this link.
https://www.summitracing.com/parts/smp-vcp113?seid=srese1&gclid=Cj0KCQiAofieBhDXARIsAHTTldpFMFNWHOg74JvWfxvIMblWfm5xIcmxke9KT_J4zDVIEYja1lJz5ZgaAhU8EALw_wcB
Then connects to the reservoir.
https://www.amazon.com/Dorman-HELP-47076-Vacuum-Tank/dp/B000COB8FA/ref=asc_df_B000COB8FA/?tag=hyprod-20&linkCode=df0&hvadid=312190333361&hvpos=&hvnetw=g&hvrand=11848653662037997508&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027230&hvtargid=pla-592635622754&psc=1®ion_id=674469
PS, this pump is located on the outside firewall and easy to see. They usually look like this link.
https://www.summitracing.com/parts/smp-vcp113?seid=srese1&gclid=Cj0KCQiAofieBhDXARIsAHTTldpFMFNWHOg74JvWfxvIMblWfm5xIcmxke9KT_J4zDVIEYja1lJz5ZgaAhU8EALw_wcB
Then connects to the reservoir.
https://www.amazon.com/Dorman-HELP-47076-Vacuum-Tank/dp/B000COB8FA/ref=asc_df_B000COB8FA/?tag=hyprod-20&linkCode=df0&hvadid=312190333361&hvpos=&hvnetw=g&hvrand=11848653662037997508&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9027230&hvtargid=pla-592635622754&psc=1®ion_id=674469
