Heater core bad?
Thread Starter
Instructor
Joined: Sep 2018
Posts: 221
Likes: 10
Heater core bad?
Turned the heat on the car today, and had a rougher idel vs the rest of the ac settings. When I shut the car off I could he what sounded like a huge air leak in the heater core. It didn’t make this sound until I turned the heat on. Is it time for a new heater core? Would keeping it in max ac mode bypass the heater core.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Try this: Raise your hood and start your engine with the dashboard "heat" control lever "off". Note the position of the arm on the vacuum solenoid. Move the dashboard heat control lever to the middle of the "heat" position. Does the arm of the vacuum solenoid change position? Is that where the leak is located?
Pro
Joined: Mar 2007
Posts: 593
Likes: 352
From: Mt Prospect IL
2025 C4 of the Year Finalist - Unmodified
The rough idle may only be the difference between the A/C compressor being turned on and off. The leak sound may be the A/C refrigerant equalizing. Both are somewhat normal. I would look to see if the car is due for a tune up or if there is anything wrong with the idle control system.
Thread Starter
Instructor
Joined: Sep 2018
Posts: 221
Likes: 10
None of your description would indicate a bad heater core. The lower heat control lever in your '84 actuates a vacuum solenoid that is located at the water tubes to the right of your air conditioning unit under the hood (on the firewall). The upper control lever for the a/c has nothing to do with this vacuum solenoid or the heater core.
Try this: Raise your hood and start your engine with the dashboard "heat" control lever "off". Note the position of the arm on the vacuum solenoid. Move the dashboard heat
control lever to the middle of the "heat" position. Does the arm of the vacuum solenoid change position? Is that where the leak is located?
Try this: Raise your hood and start your engine with the dashboard "heat" control lever "off". Note the position of the arm on the vacuum solenoid. Move the dashboard heat
control lever to the middle of the "heat" position. Does the arm of the vacuum solenoid change position? Is that where the leak is located?
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
The only time the water flow is shut off is when the temp lever is in the "cold" position. The water flow is either "on" or "off". There is no "in between". The upper lever on your control panel has nothing to do with the water flow . . . . Period!
I'm trying to answer your initial question: "Is it time for a new heater core?" The answer is "NO"! You may have other vacuum control problems, but you don't have a heater core problem. It's easy to get distracted when you don't understand how things work!
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Thread Starter
Instructor
Joined: Sep 2018
Posts: 221
Likes: 10
I am talking about the water flow shutting off in the max ac setting, funny thing is, been running it on max ac today, and I don’t have any problems. Try turning the heat on when you have it on max ac and let me know how that works for.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Team Owner
Joined: Jul 2004
Posts: 28,352
Likes: 3,253
From: Hartford WI
Turned the heat on the car today, and had a rougher idel vs the rest of the ac settings. When I shut the car off I could he what sounded like a huge air leak in the heater core. It didn’t make this sound until I turned the heat on. Is it time for a new heater core? Would keeping it in max ac mode bypass the heater core.
Thread Starter
Instructor
Joined: Sep 2018
Posts: 221
Likes: 10
Not really worried about the idel part, more worried about the noise it makes when I shut the car off on “heat” mode. Coolant system doesn’t do this when I leave it on max ac. Might be a plug in it like you said, but for now I’m not too worried, I leave ac off or max ac and it doesn’t do it.
