Thread: Hard start with heat on

Now that's it's cooling down and I'm leaving the heat on I've noticed my car is starting up kind of hard compared to usual. When the heat is in the off position it starts up normal. These are cold starts too if that makes a difference. It did this when the ac is on to but that makes sense to me. Is there something that could be causing this? I don't remember it being like this the past few years. It's also not super cold out usually around 50 when this is happening. And if I drive for a while then turn it on again after going into a store or something it starts up no problem with the heat on already.

vac leak in the hvac controls maybe.

where/how would i figure out if that's it?

maybe you can hear a hiss from the dash or some thing. smoke test might work too.

I gotta ask how is the battery?

battery was new in either march 2012 or 13 I'd have to look at it to be sure.

Also what's the best way to smoke test? Does autozone rent those out?

check the vac line that runs under the fuse box, it could be broken.

search youtube, people make em out of fog machines.

The pcm won't command the AC on until after the car is started and up and running. So that shouldn't cause an issue. Heat vs AC being on shouldn't cause an issue. The climate control if it had a leak would be defaulting to a mix of defroster and floor vents.

When was the last TB cleaning?

I've never cleaned the TB so I'm assuming it's never been done. Now that you've pointed it out Bill I do have the car on defroster or defroster/floor since it's cool out right now. But when he starts hard with the AC on it's always on the max AC option. Would a dirty TB still cause it to start hard only when the heat or ac is on and not when everything is off? I figured that having them on made it draw extra power somehow but you're saying they don't kick on until the car is running.