only defrost works

my heating system only works on high and in the defrost setting. i understand why it only works in high but why only in defrost? the heat,vent and bi-level do not work but defrost works and if i slide the switch to off it'll shut off. anyone know whats going on? also the heat isnt that warm. i checked with a thermal gun and the temps on the hoses going in and out of the heater core are like 166 on both. what could be the issue there?
thanks
ben

Having only defrost is a symptom of a vacuum leak. On a renix based system the most common place to check is the small hard vacuum line running behind the battery to the vacuum canister in the front bumper. It cracks right at the battery.

if it is cracked do i have to buy a new one from somewhere or will flexable line work? if i have to buy it will a parts store have it or only a dealer? i cant really go outside and look right now because i am in class but i wanna know where to get it before hand. thanks
ben

A short piece of hose slipped over the hard line will normally fix it.

haynesn12 said:

if it is cracked do i have to buy a new one from somewhere or will flexable line work? if i have to buy it will a parts store have it or only a dealer? i cant really go outside and look right now because i am in class but i wanna know where to get it before hand. thanks
ben

Click to expand...

You can use flexible vacuum hose. Standard stuff by the foot at auto parts stores. Find where the leak is, if it's in a hose, and replace the hose. If it's in a plastic line, you can either replace it with hose, or cut out the damaged portion and use hose that fits over the tubing. Clamps aren't necessary if it's a snug fit. Make sure it is vacuum hose, though, or it will collapse. I would recommend replacing the entire plastic run from the vacuum tank back to the nearest known good connection, if possible.

If you don't find a leaky hose, it might be a leak in the vacuum reservoir itself. this plastic tank lives behind the right front bumper. You can see it if you move aside the rubber fender liner. Sometimes minor bumper impacts etc. will crack the tank. It's especially susceptible to breaking off of the mounting feet, which can leave a hole. You can replace it, or in a pinch patch it with silicone, shoe goo, or just about anything thick and adhesive that will stop a leak.

i fixed it. turned out both lines were dissconected so i pluged em back in and now ever things works. but when i turn it on the voltage drops down to almost nine. could it be a bad blower motor or is that normal?