Old Timer

Update: I replaced the radiator and the A/C discharge hose from the compressor. Disconnected the battery for over a minute, and so far all it does is blow cold air. Heater hoses are hot. Does anybody have a diagram of which actuator does what and their location?

Now it makes more sense. I think I might quit using the tabs. I read somewhere that GM recommended to not use those anymore.

Very odd that the heater core would keep clogging up, but anything is possible.

The PCM should ground the fuel pump relay for 3 seconds when the key is turned on. After that the OPS grounds the fuel pump relay. If you are getting a foam from the fuel line the pump is sucking air, like OldCaddyTech said. Are you sure there is plenty of fuel in the tank?

Sounds like a temperature door problem if coolant looks that good.

I have a custom made screw in put in where the telescoping adjuster goes. Tighten it down and the shaft stays put. You can make one out of a threaded rod, and put a slot in it for a flat head screw driver. Tool goes right over the top of it. It's only about an inch long.

Just some late information. The spring in the EGR valves lose tension after getting hot from a lot of miles, and cause a hesitation on all the old vacuum EGR valves. Most of the time it is a TPS, but the EGR can be a culprit also. Just trying to help.

Why not just back flush the heater core with a garden hose? If junk comes out then you know what was wrong. If the core starts leaking, then replace it. Also if junk comes out, you should flush the entire cooling system, but not with the machines they have out. I personally don't think they work well. I have an old school type flusher that uses compressed air and water. Works great. Just my 2 cents.

Certainly worth a try. Thanks for the input. I have to replace the radiator this weekend, so I'll try that then. Radiator doesn't have anything to do with pulling the back seat, but I'll have the car. The wife drives it to work all week and puts 120 miles on a day, so I do what I can when I have it.

I got it from RockAuto, but the modes work fine. It is the temperature that is out of wack. It is the original. This is the second mode door actuator. The first one I removed the entire dash to replace it, this time I left the big gear assembly and just pried the actuator off the big gear. I don't ever want to pull the dash again!

I had to replace the "mode" actuator because of a stripped gear. After I replaced it, air is blowing cold and then hot out of the vents. It also switches cold and hot from side to side. I did pull the wrong actuator at first. I pulled the one to the rear of the "mode" actuator, but I put it right back on. It seems to blow out of the correct ducts, but the temperature changes dramatically without changing the temperature setting. I read that to re-calibrate the HVAC system I should disconnect the battery and short the positive and negative battery terminals together, and then run the HVAC throu

I personally got a BAFX bluetooth OBDII adapter and use it with my android phone. I got the Torque Pro app on Google Play. It also works with my Windows laptop with Scan XL. The adapter and Torque Pro cost me about $30.00 and has worked on everything I have put it on including my 2005 Deville and a 2015 Buick Regal. It is not as comprehensive as a Tech 2, but for checking codes and live data stream it works very well. Just my 2 cents.

I never could get clear information about where the tach signal comes from. It could be the cam sensor. It was a lot easier to diagnose problems when I worked in the Cadillac dealership. They have any information available you could ever need, but they don't want to give any of that out. The service manager that I worked with even treats me like a stranger. I knew the guy for about 20 years. The GM training centers were great and gave a bunch a literature when I was sent for classes, but that was a long time ago. I worked in the dealership when the nightmare 8-6-4 came out, but mostly I worked

The PCM is worth more than the car! I agree that it should be replaced, but the wife wants to just drive it. I'm not going to try and argue with her.

Fuel PSI is between 41-45 running. I spent hours with torque pro on my phone and Scan XL on my laptop with no results at all. RPM at cranking stayed around 150, which from everything I have read was normal. Having an RPM reading kind of ruled out a bad crank sensor or 2, since this engine has 2. In desperation I pulled the PCM out and pulled the connectors off. Cleaned the connectors with CRC electrical cleaner and tapped on the PCM. Reinstalled the PCM and the car cranked right up. I'm not sure if this would be a fix, but it's running fine again now. Hope this might help somebody in the futur