AC/ Heater

Discussion in 'General Chevy & GM Tech Questions' started by jrstroh_96, Sep 29, 2009.

  1. jrstroh_96

    jrstroh_96 New Member

    I bought this 04 Silverado Z71 Crew Cab. 3 months ago. Everything was good i was running around and it started to rain and the window started to fog up. So i turned heater on defrost. Now i cant get it off defrost. I can run both heater and defrost but only in defrost mode. I changged out the control unit . But nothing! I also bought a delta series flowmaster catback exhaust. I started hearing the engine reving up and down when i was in overdrive. The tach aint moving with the sound.It almost sounds like i have a stick in it and I'm in too high of gear for that rpm. Did some Googling found there was problems with both tranny and tachs in these trucks. So i took it to a local trans guy. He took it for a run and then smelled and felted the tranny fluid . He told me that since the truck came with 265 and i have 285's on it. either i do 1 of 2 things have gm reset pc for new tire size or go back to stock. If anyone can help me with my 2 lil problems. It would save my brains a lil stress. Thank you
  2. redneckarmyMP

    redneckarmyMP Epic Member 5+ Years 500 Posts

    ive ahd a smilar problem with my defrost..its done it a few times..its happened a few took a few tries to get it to switch back but it finally does every time..not sure what causes it yet
  3. sc99z71

    sc99z71 Rockstar 100 Posts

    I had the same tranny problem that you have except I didn't know what it was until it got worse and would go in and out of Overdrive. With it sometimes going out of OD and not going back in, and if I drove like that for a while I would get a really hard 1-2 shift. What is happening is your Tourque Converter is not fully locking up in OD and the 4L60E is designed to slip to a certain degree. They want to make it smooth instead of shift like a truck. I also have 285 tires. My solution was the TransGo shift kit SK4L60E put in by the local trusted tranny shop who said this is a common problem for these trannys. My buddy at work is having the same issue and is about to take it to the shop.

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