I've got a 2002 that had a leak from Heater Core for some5 or 6 months, after long drives coolant/water would sometimes leak from the front passenger side quickly, well winter came so I finally got my heater core replaced now my heat blows hot, but now I have 4 new problems, it only blows from defrost vents, the check engine light is on now (gonna go read codes tomorrow), truck makes some air leak sucking type sound from behind the dash whenever its not accelerating, and when I put it in park it idles up the down then up then down then levels out, every time, so weird.....I had none of these problems before he got hold of my truck...very very pissed...where do I start?

 

HVAC mode doors are vacuum operated. Left something loose, leaking vacuum and causing your CEL lean codes P0174 and P9171

 

Check the vacuum lines behind the battery too.

 

Thanks for the reply, after searching the net I landed on vac lines being to blame, all this happened tonight, hadn't had my truck since last Thursday so I couldn't let it rest, went under the hood to a vac line that I knew was dry rotted but connected from previous experience and it was completely broken...I'll go get some vac line tomorrow and hope that fixes it...

 

Its damn cold out here but I think I got the fix, didn't take long...will see tomorrow when auto zone opens..

 

If you fix the vacuum leak, you don't need to go to the parts store to get the codes read since we already know what they are. Just reset the PCM and resume driving normally and see what happens.

 

Oh yeah, I only went to part store to get a lil slice of vac line....it fixed the idle & HVAC issues.... Still hear a strong hissing, seaping sound though...