98 HVAC question/problem
05-03-2015, 07:59 PM
#1
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St. Jude Donor '15, '17
98 HVAC question/problem
Hi All, I have a 98 with manual climate control. It is blowing air out of all vents (heater, AC, and defrost) but will not move to only one circuit. Not sure if it is related, but I am hearing a whistling sound at cruise speed and it will go away under throttle. Are these vents totally electrically operated, or do they use a vacuum assist? Thank you for your help.
05-03-2015, 09:40 PM
#2
Team Owner
Hi All, I have a 98 with manual climate control. It is blowing air out of all vents (heater, AC, and defrost) but will not move to only one circuit. Not sure if it is related, but I am hearing a whistling sound at cruise speed and it will go away under throttle. Are these vents totally electrically operated, or do they use a vacuum assist? Thank you for your help.
Find the source of the "whistle" and you will likely find a vacuum line loose/disconnected or broken.
Be advised, the primary source of engine vacuum for the HVAC system comes off the rear of the intake manifold via a small black nylon vacuum line, and is routed inside the main wiring bundle, going down the right rear of the engine compartment. From there it breaks out of the wiring harness and is connected to a black plastic vacuum reservoir tank through a small check valve, which is located below and behind the battery (above the pcm mount). From there it goes through the firewall into the engine compartment to supply vacuum to the control head.
Since you say you can hear a whistle inside the car, you should be able to remove the console/radio surround and unbolt the HVAC control head. Pull it out slightly and you'll see a number of different colored nylon vacuum lines connected to the backside of the mode selector switch on the control panel.
Follow the whistle.
Btw, if your connection on the back of the manifold is loose (or off) you'll need to repair or reconnect it.
05-03-2015, 10:22 PM
#3
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St. Jude Donor '15, '17
On the C60 systems (such as yours), the mode select actuation is vacuum and the temp selection switch is electric.
Find the source of the "whistle" and you will likely find a vacuum line loose/disconnected or broken.
Be advised, the primary source of engine vacuum for the HVAC system comes off the rear of the intake manifold via a small black nylon vacuum line, and is routed inside the main wiring bundle, going down the right rear of the engine compartment. From there it breaks out of the wiring harness and is connected to a black plastic vacuum reservoir tank through a small check valve, which is located below and behind the battery (above the pcm mount). From there it goes through the firewall into the engine compartment to supply vacuum to the control head.
Since you say you can hear a whistle inside the car, you should be able to remove the console/radio surround and unbolt the HVAC control head. Pull it out slightly and you'll see a number of different colored nylon vacuum lines connected to the backside of the mode selector switch on the control panel.
Follow the whistle.
Btw, if your connection on the back of the manifold is loose (or off) you'll need to repair or reconnect it.
Find the source of the "whistle" and you will likely find a vacuum line loose/disconnected or broken.
Be advised, the primary source of engine vacuum for the HVAC system comes off the rear of the intake manifold via a small black nylon vacuum line, and is routed inside the main wiring bundle, going down the right rear of the engine compartment. From there it breaks out of the wiring harness and is connected to a black plastic vacuum reservoir tank through a small check valve, which is located below and behind the battery (above the pcm mount). From there it goes through the firewall into the engine compartment to supply vacuum to the control head.
Since you say you can hear a whistle inside the car, you should be able to remove the console/radio surround and unbolt the HVAC control head. Pull it out slightly and you'll see a number of different colored nylon vacuum lines connected to the backside of the mode selector switch on the control panel.
Follow the whistle.
Btw, if your connection on the back of the manifold is loose (or off) you'll need to repair or reconnect it.
05-03-2015, 10:42 PM
#4
Instructor
Thread Starter
Member Since: Nov 2013
Location: Lindstrom MN
Posts: 197
Likes: 0
Received 6 Likes
on
6 Posts
St. Jude Donor '15, '17
On the C60 systems (such as yours), the mode select actuation is vacuum and the temp selection switch is electric.
Find the source of the "whistle" and you will likely find a vacuum line loose/disconnected or broken.
Be advised, the primary source of engine vacuum for the HVAC system comes off the rear of the intake manifold via a small black nylon vacuum line, and is routed inside the main wiring bundle, going down the right rear of the engine compartment. From there it breaks out of the wiring harness and is connected to a black plastic vacuum reservoir tank through a small check valve, which is located below and behind the battery (above the pcm mount). From there it goes through the firewall into the engine compartment to supply vacuum to the control head.
Since you say you can hear a whistle inside the car, you should be able to remove the console/radio surround and unbolt the HVAC control head. Pull it out slightly and you'll see a number of different colored nylon vacuum lines connected to the backside of the mode selector switch on the control panel.
Follow the whistle.
Btw, if your connection on the back of the manifold is loose (or off) you'll need to repair or reconnect it.
Find the source of the "whistle" and you will likely find a vacuum line loose/disconnected or broken.
Be advised, the primary source of engine vacuum for the HVAC system comes off the rear of the intake manifold via a small black nylon vacuum line, and is routed inside the main wiring bundle, going down the right rear of the engine compartment. From there it breaks out of the wiring harness and is connected to a black plastic vacuum reservoir tank through a small check valve, which is located below and behind the battery (above the pcm mount). From there it goes through the firewall into the engine compartment to supply vacuum to the control head.
Since you say you can hear a whistle inside the car, you should be able to remove the console/radio surround and unbolt the HVAC control head. Pull it out slightly and you'll see a number of different colored nylon vacuum lines connected to the backside of the mode selector switch on the control panel.
Follow the whistle.
Btw, if your connection on the back of the manifold is loose (or off) you'll need to repair or reconnect it.
05-03-2015, 11:16 PM
#5
Team Owner
05-04-2015, 10:11 AM
#6
Le Mans Master
