HVAC only blows hot air

[Plumber1]

My AC / Heater is now blowing air out of the defroster vents at the windshield. No matter where I set the control it blows out the defroster only. The fan speed works fine just the selector not working. Any help where to start looking would be helpful

Thanks
Dan

 

[K0LCB]

Check for a vacuum leak, probably a hose off or broke

 

[qslim]

@K0LCB is on the right track.. The position selector is vacuum controlled, and the system is designed so that it will default to the defrost setting in the case of a vacuum leak. You probably just have a torn hose somewhere. Check your manual in the TJ Resources forum, you'll find good info on the vacuum hose routing and troubleshooting procedures.

 

[Chris]

It's likely either a vacuum leak, or a stuck blend door actuator.

A smoke test is a very effective way of finding otherwise impossible to find vacuum leaks.

 

[Plumber1]

Thanks guys for the starting points

 

[Plumber1]

Ok you guys just saved me some $$. I though at first this is going to be a long and tedious search of tiny hoses going every which way, and most likely will end up in the shop. It took about 3 min. and I found this,, one minute later a working AC system. It does seam like the fit is a bit loose and not like a nice tight fit. Since you helped my I thought well since this forum just saved me some $$ I should repay it and become supporting member so that whats I just did.

Thanks

 

[Chris]

That’s awesome news, thanks for the update and for supporting the forum!

Put a little zip tie on the end of that hose if it’s a little too loose.

 

[qslim]

Ok you guys just saved me some $$. I though at first this is going to be a long and tedious search of tiny hoses going every which way, and most likely will end up in the shop. It took about 3 min. and I found this,, one minute later a working AC system. It does seam like the fit is a bit loose and not like a nice tight fit. Since you helped my I thought well since this forum just saved me some $$ I should repay it and become supporting member so that whats I just did.

Thanks

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Nice work! A little zip tie or a dab of RTV will keep that guy stayed put.

 

[Brianj5600]

Hoses stretch over time making for a loose connection. If you have extra slack in the hose, cutting the length of the nipple off the hose will tighten up the connection.