# Heater control **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** heating\ **Created:** [February 17, 2015, 6:16pm UTC](https://community.cartalk.com/t/heater-control/89067 "2015-02-17T18:16:41Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![PapaScott1972](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/papascott1972/32/46874_2.png) [@PapaScott1972](https://community.cartalk.com/u/PapaScott1972)\ **Post date:** [February 17, 2015, 6:16pm UTC](https://community.cartalk.com/t/heater-control/89067/1 "2015-02-17T18:16:41Z")
2000 Blazer LS 4X4. 186k miles. It would seem that my heater control will only work for defrost and face-vent operation. (Just happened yesterday) When I move the controller from the off position to defrost, I can hear the system moving the flaps into position. But it no longer moves for defrost/floor or just floor control. Would changing the heater control solve this problem, or could it be a bad vacuum line? Suggestions? Ideas please? ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [February 17, 2015, 9:12pm UTC](https://community.cartalk.com/t/heater-control/89067/2 "2015-02-17T21:12:31Z")
Vacuum leak or bad actuator. Here is a video to help. [http://www.youtube.com/watch?v=Nlt9A1sp-4U](http://www.youtube.com/watch?v=Nlt9A1sp-4U) ---
**Author:** ![PapaScott1972](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/papascott1972/32/46874_2.png) [@PapaScott1972](https://community.cartalk.com/u/PapaScott1972)\ **Post date:** [February 18, 2015, 1:42am UTC](https://community.cartalk.com/t/heater-control/89067/3 "2015-02-18T01:42:59Z")
Thank you @knfenimore . I’ll have to try this. Just going to fun since we aren’t expected to get above 22 degrees all week here. ☹ ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [February 18, 2015, 3:39am UTC](https://community.cartalk.com/t/heater-control/89067/4 "2015-02-18T03:39:01Z")
Sorry that you’ll be in the cold. There is another video showing the replacement of the actuator. [https://www.google.com/url?sa=t&source=web&rct=j&ei=j8LjVJ79NtijyATPjYGIBQ&url=http://www.youtube.com/watch%3Fv%3DWiwZeJlAQdo&ved=0CCsQtwIwBQ&usg=AFQjCNFixm0\_L-XLiHJkny-\_CkQf3a3KNQ&sig2=4q2C9xyHP8DI4gI9mLZt9g](https://www.google.com/url?sa=t&source=web&rct=j&ei=j8LjVJ79NtijyATPjYGIBQ&url=http://www.youtube.com/watch%3Fv%3DWiwZeJlAQdo&ved=0CCsQtwIwBQ&usg=AFQjCNFixm0_L-XLiHJkny-_CkQf3a3KNQ&sig2=4q2C9xyHP8DI4gI9mLZt9g) ---
**Author:** ![PapaScott1972](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/papascott1972/32/46874_2.png) [@PapaScott1972](https://community.cartalk.com/u/PapaScott1972)\ **Post date:** [February 20, 2015, 6:11pm UTC](https://community.cartalk.com/t/heater-control/89067/5 "2015-02-20T18:11:22Z")
Thank you AGAIN @knfenimore ! Great video. I even have a reason to buy more tools. Lol. I’m sure I can convince a friend to let me use their garage to change it out. I will definitely be visiting my local junk yard for the part as I prefer to recycle when possible. You have been very helpful. Thank you! ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [February 21, 2015, 12:24am UTC](https://community.cartalk.com/t/heater-control/89067/6 "2015-02-21T00:24:36Z")
Glad to help. Let us know what you find. Just remember, used parts are just that, used. They can already be bad before you pull them. ---
**Author:** ![Cavell](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cavell/32/43396_2.png) [@Cavell](https://community.cartalk.com/u/Cavell)\ **Post date:** [February 21, 2015, 12:48am UTC](https://community.cartalk.com/t/heater-control/89067/7 "2015-02-21T00:48:55Z")
22F and it’s stuck on defrost?? Wow, you must be hurting real bad. You better stay home. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [February 21, 2015, 3:51am UTC](https://community.cartalk.com/t/heater-control/89067/8 "2015-02-21T03:51:37Z")
At least if it is stuck on defrost you can see, it it was stuck on floor you wouldnt be able to see out the windows unless you turned off the heat entirely, scraped the inside of the windows and opened a window partway to stop your breath from steaming them up. That is what we used to have to do with tractor trailers in the 60s and 70s when going to Watertown or Montreal. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 21, 2015, 6:50am UTC](https://community.cartalk.com/t/heater-control/89067/9 "2015-02-21T06:50:01Z")
Just curious, on this vehicle, are these vacuum actuators or some kind of electric motor actuators? ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [February 21, 2015, 7:43am UTC](https://community.cartalk.com/t/heater-control/89067/10 "2015-02-21T07:43:13Z")
vacuum ---
**Author:** ![ok4450](https://avatars.discourse-cdn.com/v4/letter/o/e9bcb4/32.png) [@ok4450](https://community.cartalk.com/u/ok4450)\ **Post date:** [February 21, 2015, 7:55am UTC](https://community.cartalk.com/t/heater-control/89067/11 "2015-02-21T07:55:45Z")
At 16 years old and near 200k miles a vacuum leak is possible anywhere. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [February 21, 2015, 8:32am UTC](https://community.cartalk.com/t/heater-control/89067/12 "2015-02-21T08:32:23Z")
Blue Blazer We have a few blazers in our fleet. I always print out the vacuum schematic before I start my diagnosis [![](http://www.john-stichnoth.com/images/BlazerSonoma/HVACScematic.jpg) ](http://www.john-stichnoth.com/images/BlazerSonoma/HVACScematic.jpg) In case you need to access the slave mode actuator, you’ll need to lower the glove box door. The service manual will not show you where it’s at If you do find out exactly which actuator is the problem, [gmpartsdirect.com](http://gmpartsdirect.com) has pretty good pictures, and lists the correct part numbers. The good news is they also use the exact same terminology as in that schematic Rockauto also has part numbers, but I’m not sure the descriptions are completely accurate. A simple vacuum pump and a vacuum gauge will also help in your diagnosis. Those tees that hold golf balls also work great for plugging vacuum hoses, for purposes of diagnosis ---
**Author:** ![PapaScott1972](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/papascott1972/32/46874_2.png) [@PapaScott1972](https://community.cartalk.com/u/PapaScott1972)\ **Post date:** [March 3, 2015, 8:02pm UTC](https://community.cartalk.com/t/heater-control/89067/13 "2015-03-03T20:02:48Z")
Thank you @db4690 That schematic will definitely help! I’m just hoping I don’t need to rip the whole dash apart to get it done. Thankfully, I don’t travel too much right now. Warmer weather is on it’s way (40’s), so I may be able to start problem solving soon!