2005-2014 Mustangs Discussions on the latest S197 model Mustangs from Ford.

Heater only blows when higher RPMs

Thread Tools
 
Search this Thread
 
Old Dec 20, 2013 | 08:33 PM
  #1  
kput's Avatar
kput
Thread Starter
4th Gear Member
 
Joined: Jul 2011
Posts: 1,207
From: NE
Default Heater only blows when higher RPMs

Title is at states. Car blows cold unless the rpm's are up. When in idle it blows cold.

I filled the coolant and haven't seen any leaks.

What could it be?
Got about 60k miles now..
Old Dec 21, 2013 | 03:17 AM
  #2  
petrock's Avatar
petrock
4th Gear Member
 
Joined: Nov 2006
Posts: 1,669
From: CA
Default

Probably the heater core. When it blows cold, where is the needle in the temp gauge? When it blows hot, where is the needle in the temp gauge?

I don’t know where the heater core is exactly on your ride, but look in the engine bay for two thick black hoses going into the firewall. When the motor is at operating temps, and you have the heater on full blast they both should be warm/hot. If one is warm/hot and the other is cold then the heater core is clogged/blocked. If both are cold then the inlet hose is clogged/blocked somewhere between the firewall and water pump.

Good luck...
Old Dec 21, 2013 | 05:01 AM
  #3  
torybella's Avatar
torybella
 
Joined: Dec 2013
Posts: 13
From: CA
Default

Probably outside temparature is too cold and maybe your idle needs to be increased.
Old Dec 21, 2013 | 05:06 AM
  #4  
Lem-06's Avatar
Lem-06
4th Gear Member
 
Joined: Sep 2011
Posts: 1,225
Default

I cant imagine the reason is simply its too cold outside, once the engine is up to temp no reason the outside temp should cool the hoses going to heater core that much.

im leaning towards petrock with this one
Old Dec 21, 2013 | 10:42 AM
  #5  
Norm Peterson's Avatar
Norm Peterson
6th Gear Member
 
Joined: Feb 2007
Posts: 7,635
From: state of confusion
Default

Possible stuck (open) thermostat.


Might want to put a scan tool on it that can read coolant temperature.




Norm
Old Dec 21, 2013 | 11:58 AM
  #6  
Nuke's Avatar
Nuke
6th Gear Member
 
Joined: Jun 2007
Posts: 16,182
From: PA to KY ('07) to IL ('09) to MS ('10) to FL ('11)
Default

I'm still in the low coolant bandwagon despite the OP saying he filled it. I suspect a pocket of air that needs to be "burped". The fact that the outlet air changes temp with RPM seems to make the other suggestions not probable.
Old Dec 21, 2013 | 02:23 PM
  #7  
kput's Avatar
kput
Thread Starter
4th Gear Member
 
Joined: Jul 2011
Posts: 1,207
From: NE
Default

I'm checking the air pocket next chance I get. That's my first step.
Then I'll go to checking heater core and the other stuff.
Old Dec 21, 2013 | 04:21 PM
  #8  
vixr's Avatar
vixr
2nd Gear Member
 
Joined: Aug 2010
Posts: 277
From: Florida
Default

I'm with Nuke...sounds like a low RPM steam pocket
Old Dec 22, 2013 | 05:24 AM
  #9  
Lethaldosage423's Avatar
Lethaldosage423
4th Gear Member
 
Joined: Apr 2008
Posts: 1,632
From: Southern California
Default

Originally Posted by Nuke
I'm still in the low coolant bandwagon despite the OP saying he filled it. I suspect a pocket of air that needs to be "burped". The fact that the outlet air changes temp with RPM seems to make the other suggestions not probable.

that would be my first guess, then possibly a stuck thermostat.

there could also be a blockage in the system and when the water pump builds pressure at higher RPM, it forces the coolant through.
Old Dec 22, 2013 | 07:26 AM
  #10  
Nuke's Avatar
Nuke
6th Gear Member
 
Joined: Jun 2007
Posts: 16,182
From: PA to KY ('07) to IL ('09) to MS ('10) to FL ('11)
Default

Originally Posted by Lethaldosage423
...there could also be a blockage in the system and when the water pump builds pressure at higher RPM, it forces the coolant through.
Possible, but the OP's not seeing any overheating due to flow blockage at low RPM.



All times are GMT -5. The time now is 12:13 PM.