No Heat, No AC (but blower motor works fine?) 2002 S40

[BenjaminS40]

I recently took my 2002 S40 to a local repair/tire shop to have a tire replaced and some diagnostics done. Before taking it to this shop, my AC and Heater had worked perfectly. Immediately after getting it back, we noticed that we were getting neither hot or cold air no matter what position the temperature knob was set at. Basically, whatever the outside ambient temperature was, that's the temperature of air we would get from the vents, regardless of how we turned the nobs. A few months ago, I replaced the blower motor resistor and for those months, both AC and heater had worked perfectly. Now, when it's cold outside, the air through the vents is cold and when it's warm outside, the air from the vents is hot. The fan control knob still works, but the temperature knob has no effect.

I took it back to the same shop and told them what had happened and they agreed to look into it. They said they reset the computer but kept getting the code 000A (i'm assuming they meant CCM 000A). They also said that to look into it further, they'd have to completely dismantle the dash and the labor would cost me a few hundred dollars.

I know it's possible that the original trip to the shop and the climate control failing could be pure coincidence but that seems unlikely. Is there something that they could have tripped while doing their diagnostics? The only thing I saw them physically remove was the air filter (they said the air filter had a crack in it).

Anyone have any ideas about this? I'm on a tight budget but I'd like to at least get the heater to work again. Thanks!

[alschnertz]

What were the "some diagnostics done" related to?

I really doubt a tire change caused your no-heat issue.

And why do they already know that they'll have to "completely dismantle the dash" to diagnose a problem?
The ECC unit slides right out of the dash.

[BenjaminS40]

I honestly don't think the shop is very competent. I live in a small town and it was the closest option. It's primarily a tire shop but they also do mechanic work. The diagnostics were related to a rattling noise at higher speeds and some engine problems I've been having. They couldn't figure out what the rattling noise was but they said one of my cylinders was misfiring. I replaced the ignition coils today on my own and it runs great now.

The rattling noise remains but it's been occurring for a couple months. I'm guessing it's either a suspension related issue or the motor mount. They said that both the suspension and motor mount were fine but I don't exactly trust their level of expertise at this point. I'm pretty sure their main goal is to sell tires.

I have no idea why they would have to "completely dismantle the dash". They spent about an hour trying to figure out the problem before they told me that.

[alschnertz]

Check the front stabilizer bar end links regarding the rattling. No guarantee, but it's a pretty common wear item.

Re. the A/C, I guess at this point I'd start with the basics. Check all the fuses, clean the filter and try changing the HVAC settings with the key in position II, but the engine not running so you can hear if things are actually moving.
I'm not too familiar with the inner workings of the HVAC system but agree with you that it seems too coincidental that it failed after the service.

Maybe you can look under the hood, especially around the airbox, and see if there are any vacuum lines that are disconnected.