rear heat
Elder User
Joined: Aug 2003
Posts: 624
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From: Houston, TX
If you have heat in the front, then it's a good possibility that you might have a vacuum line problem to the rear unit. The flaps that direct the air flow over the A/C evaporator or the heater core are vacuum operated. A break in the line will give the symptoms you are describing.
Post Fiend
Joined: Apr 2005
Posts: 5,720
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From: Washington state
from ford service cd
With the auxiliary heater and heater-air conditioner systems functioning in either the VENT or A/C positions, a vacuum-operated water valve shuts off water to the auxiliary heater core.
the vac. water valve for the rear heat is located under the body in the heater hose going into the floorpan under the rear heater
hose may also be pinched off around engine or underbody
With the auxiliary heater and heater-air conditioner systems functioning in either the VENT or A/C positions, a vacuum-operated water valve shuts off water to the auxiliary heater core.
the vac. water valve for the rear heat is located under the body in the heater hose going into the floorpan under the rear heater
hose may also be pinched off around engine or underbody
Posting Guru
Joined: Jun 1999
Posts: 1,642
Likes: 6
From: Northern California
Also check for collapsing vacuum hoses. Over time, sometimes those hoses get weak. When activated, they collapse somewhat, almost causing a kink or at least an obstruction.
Then when inspecting, heater and engine off, they look perfectly fine.
You might want to change those regardless. Not a common thought, when doing maintenence on the rear heater. I would not be a bit surprised if they are the factory items, and have never been touched.
You'd be surprised the number of drivability problems caused by old, weak, collapsing hoses in all older vehicles. Sometimes it's almost like pinching a line off with your fingers, or with a clamp. Then when you're going nuts looking elsewhere, the solution is a simple fix.
Good luck.
Then when inspecting, heater and engine off, they look perfectly fine.
You might want to change those regardless. Not a common thought, when doing maintenence on the rear heater. I would not be a bit surprised if they are the factory items, and have never been touched.
You'd be surprised the number of drivability problems caused by old, weak, collapsing hoses in all older vehicles. Sometimes it's almost like pinching a line off with your fingers, or with a clamp. Then when you're going nuts looking elsewhere, the solution is a simple fix.
Good luck.
Post Fiend
Joined: Oct 2005
Posts: 5,242
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From: Kiev, Ukraine
I've just installed auxialy heater from bus. Had problem with air in heater core. I disconnected 1 hose, ran engine and wait till coolamt start leaking from heater core and immediatly connected hose (floor was kept dry).
P/S. I did it with not warmed up engine. Hands were not cooked.
P/S. I did it with not warmed up engine. Hands were not cooked.
Posting Guru
Joined: Jun 1999
Posts: 1,642
Likes: 6
From: Northern California
Excellent suggestion, PABLO! I would also say, experience like you just described would not be seen in any service manual, or shop manual either.
Dale Inman once said to a reporter (Inman built the 200+ MPH NASCAR Dodge Race V8s Richard Petty RULED with in the early to mid 1970s) Inman said: Much of my race car engine building is in my head, and in my personal notes. I know what works and what doesn't work. I've read numerous engine manuals, and half of it's engine procedures is either not mentioned, or shortcuts to make things better, are not mentioned. Yet, much of what I know is in my mind".
He knows his stuff. Petty is the NASCAR King with 200 victories and 7 NASCAR Championships...
Your post there reminded me the wisdom of Dale Inman with Petty Enterprises. (He is now retired, but every so often, I see this racing icon at the racetrack with King Richard...)
Ed http://www.nascar.com/2007/news/feat...tty/index.html
Dale Inman once said to a reporter (Inman built the 200+ MPH NASCAR Dodge Race V8s Richard Petty RULED with in the early to mid 1970s) Inman said: Much of my race car engine building is in my head, and in my personal notes. I know what works and what doesn't work. I've read numerous engine manuals, and half of it's engine procedures is either not mentioned, or shortcuts to make things better, are not mentioned. Yet, much of what I know is in my mind".
He knows his stuff. Petty is the NASCAR King with 200 victories and 7 NASCAR Championships...
Your post there reminded me the wisdom of Dale Inman with Petty Enterprises. (He is now retired, but every so often, I see this racing icon at the racetrack with King Richard...)
Ed http://www.nascar.com/2007/news/feat...tty/index.html
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Elder User
Joined: Dec 2002
Posts: 624
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From: Georgia
I hate to ask but, is the control in heat or defrost? It needs to be to have heat in the back. In my first A-Star, my wife put the control in MAX and turned the heat all the way up. It was nice and warm up front but she about froze the people in the back before they turned the fan off.
MAX is for Max A/C. She wanted max heat.
In the back, if the fan is blowing out the top vents you will not have and heat in back. You should have warm/hot air coming from the floor vents in the back.
Check the simple things first. Make sure you have the control set to heat. Check where the air is coming from. It it's the top vents, you have a control problem. Look at the vacuum. If it is coming from the floor vents, Check the water flow to and from the heater core.
MAX is for Max A/C. She wanted max heat.
In the back, if the fan is blowing out the top vents you will not have and heat in back. You should have warm/hot air coming from the floor vents in the back.
Check the simple things first. Make sure you have the control set to heat. Check where the air is coming from. It it's the top vents, you have a control problem. Look at the vacuum. If it is coming from the floor vents, Check the water flow to and from the heater core.
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Elder User
Joined: Aug 2003
Posts: 624
Likes: 0
From: Houston, TX
Originally Posted by tom_foreman
I hate to ask but, is the control in heat or defrost? It needs to be to have heat in the back. In my first A-Star, my wife put the control in MAX and turned the heat all the way up. It was nice and warm up front but she about froze the people in the back before they turned the fan off.
MAX is for Max A/C. She wanted max heat.
In the back, if the fan is blowing out the top vents you will not have and heat in back. You should have warm/hot air coming from the floor vents in the back.
Check the simple things first. Make sure you have the control set to heat. Check where the air is coming from. It it's the top vents, you have a control problem. Look at the vacuum. If it is coming from the floor vents, Check the water flow to and from the heater core.
MAX is for Max A/C. She wanted max heat.
In the back, if the fan is blowing out the top vents you will not have and heat in back. You should have warm/hot air coming from the floor vents in the back.
Check the simple things first. Make sure you have the control set to heat. Check where the air is coming from. It it's the top vents, you have a control problem. Look at the vacuum. If it is coming from the floor vents, Check the water flow to and from the heater core.
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