Help with Heater problem

libertyspike138 · 11-23-2008, 04:37 PM

My heater has the option to blow heat out of the following.
Main vents, Main vents & Floor, Floor, Defrost
The problem is this is what it blows.
Floor, Floor, Floor, Defrost
I can't get any heat out of the main vents.
I made sure the heater controls are fine. Obviously the blower motor and heater core are fine. I traced all the vacuum lines from the controls to the corresponding canisters and made sure they are moving properly. A while back the heater only worked on high so I replaced the resistor pack from a salvage yard. If I shut the heater completely off and then turn it on a low speed I will get heat out of the main vents for a few seconds and then hear it close. Please Help!!!

abg · 11-24-2008, 04:37 AM

You don't state the year or make of car. My Chevy had a similiar problem and it was the actuator for the vent. Chevy uses electric motors with plastic gears. One of the gears cracked.

libertyspike138 · 11-24-2008, 05:32 AM

This vehicle is a 94 Dodge Caravan. There are 3 actuator's that are vacuum controlled. I can see them move properly and I can disconnect the vacuum and move them manually but there is no change.

dodgemechanic · 11-28-2008, 09:09 PM

You should get a vacuum pump and see if you can move the doors if they are vacuum actuated. Unfortunately I have replaced many blend and recirc doors in the housing units that were cracked at the pivot points. How are you sure the heater core is good?

curious99 · 11-29-2008, 06:56 AM

try checking the vacuum source to the heater ,under the hood.if the hose is loose,damaged,or the vacuum check valve is,it may be causing your trouble.the check valve is available at some auto parts stores.it is installed inline on the vacuum supply ,and you can test old ones,or verify correct installation of valves by trying to blow gently thru them with your mouth.it should flow in one direction only,towards the engine.if it flows in both directions,then the check valve is no good.all heaters are designed to default to defrost (you usually get a little airflow to floor also)so at least you can see,when there is a malfunction in the heater,or vacuum supply.i hope this is helpful.

11-23-2008, 04:37 PM	#1 (permalink)
libertyspike138 Registered User Join Date: Nov 2008 Posts: 2 OS: XPSP2	Help with Heater problem My heater has the option to blow heat out of the following. Main vents, Main vents & Floor, Floor, Defrost The problem is this is what it blows. Floor, Floor, Floor, Defrost I can't get any heat out of the main vents. I made sure the heater controls are fine. Obviously the blower motor and heater core are fine. I traced all the vacuum lines from the controls to the corresponding canisters and made sure they are moving properly. A while back the heater only worked on high so I replaced the resistor pack from a salvage yard. If I shut the heater completely off and then turn it on a low speed I will get heat out of the main vents for a few seconds and then hear it close. Please Help!!!

11-24-2008, 04:37 AM	#2 (permalink)
abg Registered User Join Date: Aug 2008 Posts: 10 OS: xp	Re: Help with Heater problem You don't state the year or make of car. My Chevy had a similiar problem and it was the actuator for the vent. Chevy uses electric motors with plastic gears. One of the gears cracked.

11-24-2008, 05:32 AM	#3 (permalink)
libertyspike138 Registered User Join Date: Nov 2008 Posts: 2 OS: XPSP2	Re: Help with Heater problem This vehicle is a 94 Dodge Caravan. There are 3 actuator's that are vacuum controlled. I can see them move properly and I can disconnect the vacuum and move them manually but there is no change.

11-28-2008, 09:09 PM	#4 (permalink)
dodgemechanic Registered User Join Date: Nov 2008 Posts: 5 OS: windows xp	Re: Help with Heater problem You should get a vacuum pump and see if you can move the doors if they are vacuum actuated. Unfortunately I have replaced many blend and recirc doors in the housing units that were cracked at the pivot points. How are you sure the heater core is good?

11-29-2008, 06:56 AM	#5 (permalink)
curious99 Registered User Join Date: Mar 2007 Location: delaware? Posts: 16 OS: xp home	Re: Help with Heater problem try checking the vacuum source to the heater ,under the hood.if the hose is loose,damaged,or the vacuum check valve is,it may be causing your trouble.the check valve is available at some auto parts stores.it is installed inline on the vacuum supply ,and you can test old ones,or verify correct installation of valves by trying to blow gently thru them with your mouth.it should flow in one direction only,towards the engine.if it flows in both directions,then the check valve is no good.all heaters are designed to default to defrost (you usually get a little airflow to floor also)so at least you can see,when there is a malfunction in the heater,or vacuum supply.i hope this is helpful.