HVAC not working properly

BARDIFEROUS

MEMBER
2000 DODGE CARAVAN
3.0L
V6
AUTOMATIC
148,000 MILES

A/C works fine. FYI, the radiator, cap, thermostat are all working well, and coolant is full.

Details:
1) No heat; switching from cool to heat is warmer, but not even close to 70 degrees, unless the ambient temperature is 70 or warmer.
2) When sliding the (single, not dual) cool/heat from cool to heat, the volume (even at high) drops more than 50%.
3) Fan setting 4 (of 5) is the same as Off.
4) I have attempted the Control Panel reset suggested elsewhere; when it is done, the Recirc and A/C On/Off lights are flashing.

Does this suggest a failure with the entire Control Panel or something else?

9 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Yes. The A/C and recirc door flashing means the cooldown test failed so we are going to need to run through this info.

https://www.2carpros.com/articles/car-heater-not-working

This may need a control module but there are other possible causes, so I am attaching the testing below.

Please run through this and let us know what other info you need. Then let us know what happens and we can take next steps.

If the cooldown test fails, then we need to check the A/C pressures so here is a guide that will help with this.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Please let us know what happens. Thanks

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Thursday, October 21st, 2021 AT 4:00 PM

BARDIFEROUS

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Thank you for your reply. I have ordered a replacement panel as there are too many things going wrong at the same time, as I listed. They all seem to be related to the panel that isn't resetting properly.

I will report back after that.

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Friday, October 22nd, 2021 AT 9:29 AM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. Sounds great. Yes, please let us know how it turns out. Thanks for letting us know.

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Friday, October 22nd, 2021 AT 3:00 PM

BARDIFEROUS

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I purchased a used replacement control panel and, after replacing, there was absolutely no change in behavior. I think the odds are slim that, even though it was used, the second control panel would be defective in the same ways as my panel.

So, perhaps the fan speed has to do with a relay? The change in air speed (when changing from cold to hot, not changing the fan setting), I have no idea, a blend door actuator? And the lack of heat, problem with the heater core.

My next step would be flushing the heater core. Thoughts?

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Tuesday, October 26th, 2021 AT 6:29 AM

KASEKENNY

MECHANIC
18,907 POSTS

These flashing lights mean you are failing the cooldown test, so we need to run through this info I am attaching in order to figure out what is next.

I doubt flushing the heater core will change anything so take a look at this info attached and let me know what you find.

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Tuesday, October 26th, 2021 AT 7:55 AM

BARDIFEROUS

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KaseKenny1,

Reran the tests and this last time they didn't blink at the end. Thank you for providing these instructions (are they online? Link?), But I found them not complete and a bit hard to follow. I often give instructions, and I know these weren't your own, so I'm not criticizing you! In any case, no change in the operating status.

Haven't flushed the heater core or changed any relays but might try to replace a fan relay if there is one.

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Wednesday, October 27th, 2021 AT 1:44 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. If you reran the test and the lights did not flash at the end, then this means it passed.

As the A/C lights and recirc lights still flashing all the time now? If you just don't have heat, then have you removed the blend door actuator and move the door manually to see if the door can actually move to give full heat? If so, then the actuator is clearly not moving. This also proves the heater core is not the issue.

Another way to prove a possible heater core issue is to measure the temperature of the lines going in and out of the core. They should be pretty close in temperature. If not, then you have a restriction.

However, if you are willing can you get a video of what is happening when you run this test?

Press the A/C and Wash button at the same time for 5 seconds and all the lights should come on.

Then the A/C and recirc should flash one at a time and if all the lights go off and do not come back on then it passed the test.

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Wednesday, October 27th, 2021 AT 3:18 PM

BARDIFEROUS

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Videoed the test, twice. First, with fan off; second, with fan on high. First one finished with A/C and Recirc flashing. Second finished with all lights going out.

No change in any of the issues.

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Tuesday, November 2nd, 2021 AT 5:14 PM

KASEKENNY

MECHANIC
18,907 POSTS

Perfect. You are in fact failing the cooldown test. I suspect you have an issue with the evaporator temp sensor.

The first thing we need to do just so that we are sure this is the issue is make sure the A/C pressures are correct. Due to you have an issue with changing temperature of the air I don't think this is going to be an issue but we should make sure as it is pretty easy to rent a set of manifold gauges and hook them up just to make sure the compressor is working properly.

However, take a look at the last two attachments. This address what I suspect your issue is. When you fail the cool down test and the A/C system is properly charged, it has you address the temp sensor.

Based on all this, I suspect this probe/sensor will need to be replaced.

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