2007 Tahoe evaporator replacement

Anyone ever replace the front evaporator core on one of these GMT900 Tahoes? The manual calls for me to remove both front seats and then the dash, but I’m wondering if I can get away with not removing the seats?

Yes you can actually just remove the steering column and release both side of dash- and tip the right side forward and hang it from the shoulder strap- and work from in behind it.. done it many times-- be careful not to turn steering wheel relative to steering column- use masking tape to assure there is no rotation upon re-installing steering column- otherwise you will get the dreaded ride/suspension code- because the steering wheel has a rotator sensor that knows when it is at "0" and at -540 or +540 degrees- if you let it turn, it thinks it is at 270 degrees while driving straight- and really messes things up..and sets codes. took two trucks for me to realize what happened.

The dash will hang- but you'll need to work around it- if an auto climate control- watch for temp sensors to pull out of ductwork that you did not know about- be sure to install them back in-- there is one above gas pedal that no one ever seems to see first- and it pulls out and dangles and you say WTF. If you have a helper it may well be just as easy to pull the whole dash out.

Don't ever let the owner see his truck with dash out-- they almost faint.

I won't pull an evaporator without 3 positive tests for leaks-- one is I must see dye in condensate dripping, or in drain tube-- another is I need to have my sniffer go nuts in the drain tube, and also in the center vent on low fan speed after a 2 hour soak minimum. Sometimes they are so bad you can smell the oil and refrigerant- and see the dye on the garage floor. If you hear hissing, you are golden. Never do you want to pull the HVAC case apart and see no evidence-- I am always thrilled when I see the massive green dye on or around the evaporator itself.

Got it, thanks for the info. Yeah I agree with you on verifying the leak location prior to pulling apart the whole dash. I put dye in the system about a month ago and I’ve been searching all over with both UV light and with the sniffer, found nothing. finally had the sniffer go crazy on the interior vent after letting it sit for a couple hours and then starting with the fan on low.

Do you recommend just using the steering wheel lock to keep the wheel from rotating?

That can help- just don't let steering wheel to steering column relation change- you'll take out the pin at the universal joint and it can spin inside the column if not locked or held in place.

Well I finally made time to do this job...Thanks for the tips, they helped, but what a pain in the rear! Took me 7.5 hours after all said and done.

A few notes:
1) Once I was able to swing the dash back away into the “service position,” Removing the HVAC asesembly was difficult. Pretty much all of the fasteners/studs holding the assembly to the firewall are difficult to access, requiring removal of the battery, battery tray, A/C accumulator, and plastic engine cover and intake hose assy. One of the studs holding the hvac assy in place was located directly behind the engine intake plenum, which has a plastic back cover that, from my standpoint, made it impossible to access. I ended up cutting through the HVAC assy standoff holding the stud with a sawzall from the cabin side to free it.

2) Contrary to the Haynes manual, the heater hoses do NOT require a special tool to disconnect. Rather, they are quick disconnect via pinching of the tabs on the hose...not sure if this is unique to the 2007, the police model, or what but it cost me a good hour trying to figure this out.

3). Once I got the HVAC assy out and onto the floor, I realized I had to drill out the plastic rivets to open the assembly and replace the evaporator. At least they made provisions to install screws once this has been accomplished...but I had to dig into my bucket of junk fasteners to find ones that were suitable.

4). My replacement evaporator core appeared to be pressurized?! Found this out once in place and as I was loosening the foreign material exclusion covers that come preinstalled. The first one I loosened blew off violently. Do not understand why this would be the case.

One of the top 3 hardest jobs I’ve done.

Alex

They pressurize the evaps/condensers and other a/c components to give customers the warm and fuzzy feeling, that this particular component is good and does not leak upon installation. Less blame . less warranty, that way..sometimes they use vacuum instead of pressure- you can tell id there in no bolt in plug- vacuum does not need anything to hold the plug in, while pressure does.

Good that you got er' done. Now if you had it to do over you can increase your time and by the 10th one you do, you can actually make money on it- (as a mechanic would say). Then comes another model with a whole new set of changes....

It is alway a thrill, to not get any SES codes and no squeaks, rattles, and everything works ok on the test drive when finished.

And I do these for fun, not for a living.....how bad is that....I enjoy saving family and friends a few hundred dollars, while I make a few hundred...

They pressurize the evaps/condensers and other a/c components to give customers the warm and fuzzy feeling, that this particular component is good and does not leak upon installation. Less blame . less warranty, that way..sometimes they use vacuum instead of pressure- you can tell id there in no bolt in plug- vacuum does not need anything to hold the plug in, while pressure does.

Good that you got er' done. Now if you had it to do over you can increase your time and by the 10th one you do, you can actually make money on it- (as a mechanic would say). Then comes another model with a whole new set of changes....

It is alway a thrill, to not get any SES codes and no squeaks, rattles, and everything works ok on the test drive when finished.

And I do these for fun, not for a living.....how bad is that....I enjoy saving family and friends a few hundred dollars, while I make a few hundred...

I see thanks, guess I know the evaporator is leaktight then!

Yeah, knowledge is power right? Now that I know every step and the learning has been absorbed, could probably knock that job out again in two hours. Hopefully won’t be doing it anytime soon LOL.

Thanks!

Alex

The manufacturer most likely pressurized the coils with Nitrogen gas to prevent corrosion .. when I did the ac work I would blow out any coils with this gas .. then put the vacuum pump on .. any mess in the coils will mess up the compressor and the orifice..