heater blows cold on passenger side AND p0171 bank 1 code. Related?

[1998lesabre]

I have two issues on my 1998 LeSabre Limited.

1) Heater blows nice and hot on driver's side and small backseat vents (on back of armrest) BUT blows nothing but COLD air on passenger side. This is true upper, middle, lower vents.

2) The check engine light just recently popped a p0171 code, bank 1.

Is there any chance these are related (vacuum leak)? If anyone has any ideas for fixing either/or, I would appreciate any guidance.

 

[HotZ28]

The P0171 could be related. The best way to verify if an A/C system leak is the cause, would be to remove the vacuum line from the UIM that goes to the vacuum tank and plug the fitting on the manifold then take it for a drive to see if the code disappears. If you have a capable scanner, you can watch the short term fuel trim readings while at idle. They should be 5% or less. Another way to test the A/C vacuum system for leaks, is to use a brake bleeder on the hose going to the vacuum tank and pull a good vacuum to see if it holds. If not, you have a leak somewhere. It could be the vacuum lines going to the vacuum tank, the tank itself, vacuum line from the tank to the inside programmer, programmer manifold, vacuum lines from the programmer to the actuators, or one or more of the actuators. http://www.wholesalegmpartsonline.c...odel=14443&modelYear=1998&ukey_category=19390

 

[Lubener]

A recent experience on my 97. I had a plastic vacuum line about 10 inches from the vacuum reservour, rub thru at a sharp piece of sheet metal. It was poorly routed where it curved around towards the tank.Completely cut, I didn't have any codes but HVAC acted strange, heard a whistling noise at times, and idle was a little rough. Worth a look.

 

[1998lesabre]

Appreciate the advice. I will be working on this tonight and this weekend and report back,

 

[1998lesabre]

UPDATE: I really think the heater issue is related to bad blend door actuator, and will be working on it this weekend.

However, the p0171 code has been coming and going. Currently, it is not showing at all. I do plan to run some tests this weekend to see if I can pin down what it might be.

 

[1998lesabre]

Just wanting to raise this up again. Here are the pertinent facts about this Buick LeSabre 1998 Limited -- which I got in August with 38,000 miles and now has about 45,000. I am new to DIY on vehicles and bought this in part because I want to learn and willing to try with so little invested (paid $2,400 for it).

1) For about the last 2,000 miles, ever since the only extended trip I have taken (250 miles each way over Christmas), the p0171 code showing lean bank 2 comes on and off -- 65% of the time on, 35% off. It always comes on within 5-10 miles of filling up the tank. It almost always disappears at about a 60%empty/40%full.

2) Last oil change, it was clear that oil is being lost somewhere but NOT from the gasket or drain pan. Seems to be in internal leak. Absolutely no oil drips onto driveway, parking lot, etc. So it must be leaking very lightly internally while engine is running and in motion.

3) Recently, the CHANGE OIL SOON light has come on and stayed on -- according to the manual, the computer does detect when oil has degraded. Although it was not the CHECK OIL LEVEL light, I did see was almost a quart low and so I have topped it off.

4) While I believe this could be the intake manifold gasket issue, I have sprayed and sprayed with carb cleaner and noticed no difference in rpms. In general, the car does not idle roughly -- seems very normal to me. No real issues at all, in terms of noticeable symptoms.

Appreciate any further thoughts on this. My other issue is that relationship with very trustworthy regular mechanic for years has been very much -- "you just do whatever it takes". So while certainly it's possible for me to adjust the relationship to "diagnose for me and i'll fix it myself," his is not the type of shop where that's customary.

Thanks.