Ok here it is. I have a 1991 Trans am with the 5.0 Tune Port in it. It has the auto 700r tranny in it.

Question. I am currently trying to get the a/c to work in it. I have had it prof. charged and coverted and also do it myself after find out i could. Also i would like to inform everyone that i have no experence in a/c systems on cars what so ever. My question is. behind the huge silver canister that holds the freeon... Right behind I can feel cold air coming from behind it out of that big black box connected to the firewall. There is a inch or so gap all the way down and seems to have maybe some sort of fiilter? Is this normal? cause i can not get it to blow out cold air. on a cool day it will but on a warm day it only blows out luke cool air and i'm trying to figure out what i need to replace to get it to start blowing cold air. I've tried different psi and a number of different things. I just need to know if cold air ( which is colder than what is blowing out of my vents ) is normal or do i need to take it all apart and fix something.


Problem: after sinking a lot of money into different things ( and by the way this is my first tpi car so i've done a lot of trial and error until i found this site ) and got everything perfect but one thing and this does not seem right to me but unforsure and that is why i'm asking.

When i start my car ( don't matter temp ) and let it idle down a little and throw it into gear and go ( if i just let it sit there and idle and don't move the car it idles fine with no miss ) it runs fine but when i start to stop ( and it don't matter if i've went a mile or 100 cause i've tested ) it will be idling high. Its around 800 or so and if i stay stopped for a bout 2-3 seconds ( have not timed but seems to be very constant ) it will idle down to about 600 where it should be but then begin to have a small miss. its like something is telling the computer to close my iac all the way and then air is just being sucked in through my flaps. I have replaced the EGR , TPS, IAC. Everything is set and cleaned out. After it does it the first time it will not do it again until i shut the car off and repeat the same steps. If i let my car sit and idle all the way down which it takes like 10 sec or so and put it in drive sometimes it will do it and sometimes it will idle at 600 where is should. Tired different things and could not figure out what changes the situation. I guess whatever mood my car is in LOL. Also If I come to a complete stop for only a sec and then take off it stays idleing up and when i put on the brake to stop i can feel the car still wanting to go and i think that is cause i have my air adjusted to high but i have to keep it running after it idles down. Also when it drops down, its not like a super fast drop. It drops from like 900 or 800 to like 7000 for a split second and then drops the rest of the way down.

I've been going through the chiltons book cause everyone i know has never seen this before but i don't know a lot of good mech. either that know more than me. It just doesn't seem right to me.

I was thinking its something with the computer reading my speed but my speedo works and has no jumps or dead spots but what about the vss buffer?
and what does the vss buffer do?

LIst of things replaced
Fuel Filter
plugs - a/c delco tired plugs gapped and ungapped ( same responce and everything )
wires - bocsh 8 mm
coil - msd
cap and rod. - accel hi performance
EGR valve - bought from dealer
TPS - autozone but its set to .54 idle and and 4.30 WOT
Also about the tps, its none adjustable but if i just bolt it up its at like .88 on idle so i had to do some improvments to get it to .54v I called the chevy deal and got the orginal oem # cause it had the wrong tps on it in the first place but it would take them a week to get it and autozone or oreillys ( can't remeb er which ) had it then and i need it then.
IAC and when had plentum off cleaned EVERYTHING really good

Also when i took it to the deal to have them take a look and see if they could just tell me what was wrong with it. He thought it was a coil in a injector going bad and that would make sense but doesn't do it until it idles down. and if i would sit and take it back up to 800 after the idle down it still misses. But if i don't let it idle down at a stop then it don't.

If need more info i'll be happy to provide what i can

Thanks
Derrick

 

First, the AC evaporator case. The "filter" you may be seeing inside the case is probably the face of the evaporator core. There should be a wad of semi-soft putty packed around the larger diameter line coming out of the case to eh accumulator. You can use a product called "Duct Seal" sold by GB Industries. Many better hardware stores ("Hardware store" doesd not include Home Depot, etc.) will have it. Electricians use it to seal conduit bodies in XP systems. ear off a chunk, knead it in your hands, and start forming it around the line and hole in the case until it is filled and sealed.



As for the idle, the stock programming has several portions which add idle RPM steps on deceleration, while creeping to a stop, while the AC compressor is on, while the electric cooling fan is on, and several other program steps. The idle will normally be a bit higher after coasting to a stop because the programming is trying to prevent stalls. During the deceleration phase, fuel is cut off to prevent backfire. As you approach no road speed, fuel is again applied and the idle steps may be a bit higher to make sure there is no stalling. That is all normal, and most people don't even notice it happening.

The misfire you notice once the idle has returned to the target RPM (600)_ could be due to several causes, including compression problems, weak ignition, poor fuel delivery (injectors or fuel pressure), fouled spark plugs, and any number of the usual suspects. The fact that you don't notice it as much at 800 RPM is that the engine is rotating fast enough to have a kinetic/gyroscopic effect, and will tend to stabilize and vibration from misfire.

 

ok, figured out the missin problem. the harmonic balancer was off and timing had jumped one tooth so i am going to be replacing the chain and gears. and i will be posting a new thread on suggestions for that but back to my ac.

Where the line comes out of the accumulator to the evaporator. On the case for the evaporator there is a bout a inch to inch and half gap from the line down where i can see what seems to be a filter. When the a/c is on cold air comes out there and is much colder than blows out the vents. I am about to replace my compressor cause the bearings are about shot and it makes my belt jump alot when on. The tensioner moves a great deal so i am taking one off my old blue truck that i know still works. So is that space normal or should i be finding a new box or plugging that big *** crack? If need be i can borrow a friends dig. cam and take a picture and show u

THanks Derrick

 

I nderstand the gap, and that's where the duct seal compound is useful.

 

ok, just want to make sure before i do it. It should be sealed off... And this might help me get colder air out the vents?

Thanks
Derrick