NO HEAT in Michigan

Help,
My 1997 GMC Jimmy has no heat. I have tried everything from changing theromstats, too radiator flush. Still only cold air blows out. I tried to changing heater core but can't get the one last screw off dashboard to get to the heater core, I can feel it but can't find that last screw??
Is it true I may just need to do a reverse flush on radiator? Does anyone know where I can get a dashboard layout of all screws on the GMC?
Or What's the easy way of getting to the heater core? Help it cool in Michigan & I've already spent 16.5 hours last weekend.

Hey,i Had The Same Problem Last Year,i Had To Take The Top Hose Off The Firewall,and Bleed The Heck Out Of It ,i Was So Very Airlocked It Wasnt Funny And I Know About Cool Im In Northern Maine So Try That Good Luck

Hey,i Had The Same Problem Last Year,i Had To Take The Top Hose Off The Firewall,and Bleed The Heck Out Of It ,i Was So Very Airlocked It Wasnt Funny And I Know About Cool Im In Northern Maine So Try That Good Luck

Thanks, I just had a reverse heater core flush and I now have heat again.... Thanks everyone! I just saved $600.00. It only costed me $45.00 for the reverse flush.

Thanks, I just had a reverse heater core flush and I now have heat again.... Thanks everyone! I just saved $600.00. It only costed me $45.00 for the reverse flush.
Where did you get the reverse flush done? I called Jiffy Lube, but they had not heard about reverse flushing.

I have the same problem with my 99. I was at the dealer before the holidays and they said there is a service bullitan for that problem. I'm trying to make an appt. for this week. Hopefully they will also find the problem with the outside air blowing therugh the panel vents under load too.

Any local radiator shop will do a reverse flush. My problem was from the hose too the heater core after a traditional radiator flush. It was clogged the radiator show only charged $45. Radiator shop in Ferndale, MI.

OK heater was flushed and now I have heat again. The dealership did it for free. I do have a 6 yr 100,000 mile bumper to bumper warranty though. Now I hear the water bubbling through the heater core when I first accelerate.

Help,
My 1997 GMC Jimmy has no heat. I have tried everything from changing theromstats, too radiator flush. Still only cold air blows out. I tried to changing heater core but can't get the one last screw off dashboard to get to the heater core, I can feel it but can't find that last screw??
Is it true I may just need to do a reverse flush on radiator? Does anyone know where I can get a dashboard layout of all screws on the GMC?
Or What's the easy way of getting to the heater core? Help it cool in Michigan & I've already spent 16.5 hours last weekend.

To get at the heater core in my 1991 jimmy I had a 1 screw problem, I had to take out the stereo to get at it, also if i had to change one again, Iwould take the front seat out, hope this helps...

UPDATE

After 5 dealer flushes and 1 thermostat replacement I still loose heat afer a week or 2. I think it may be faulty dealer workmanship or could there be something someone is missing