Does the A/C system affect the ECT before engine startup?

RUBLEJ

MEMBER
2001 CHEVROLET PRIZM
145,000 MILES

I just repaired my EVAP system (bad solenoid, DTC P0446) and now I'd like to get it emissions tested. The problem is that I've been driving the car around for a few days now and the EVAP test won't run (I/M status OFF). I've followed the checklist required for the test initiation, however still nothing. I believe this problem has something to do with my ECT. In order for the EVAP test to run, the car needs to be running from a cold start (ECT < 2C). I have a scan tool that I use and even after an overnight cooldown my ECT is still around ambient temp before engine startup. One caveat, though, is that my A/C system is inoperable (my condenser has a leak). Will this preclude my ECT cooling down to < 2C and therefore the EVAP test? I'd really like to not have to repair my A/C at this moment, but if that's what it takes I'll do it - I'd just like to be sure that it will finally enable my EVAP test to run. Thank you!

Jim

3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

No, will not effect the ac system

temp should be outside temp. It needs a 8 hour off time. Then it has to heat up to normal operating temp, be in overdrive or high gear and the fuel tank between 15 and 85 percent. You cannot turn off the motor either while setting. The car needs to be at 55mph, high gear, temp up and fuel tank at proper level.

Roy

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Sunday, August 5th, 2012 AT 6:26 PM

RUBLEJ

MEMBER
2 POSTS

Thanks, I'll give that a shot. The parameters I have are slightly different:

- fuel 1/4 to 3/4
- pre-startup ECT < 2*C (cold start)
- ECT warmup to at least 70*C before moving
- drive around for at least 20 mins before test
- a few more little things that don't matter

Then the test initiation goes like:

1. Start & warmup engine
2. After 20 min driving, accelerate to 30-50mph and maintain for 3 min.
3. Decel to 0mph and hold brake for 1 min while in drive (auto trans)
4. Accel to 40-45mph for 1 min.

So far no luck but I'll try the 55mph speed you suggested after my engine cools down again.

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Sunday, August 5th, 2012 AT 6:38 PM

ASEMASTER6371