Ive a problem with the a/c on my 98 chevy lumina

[1979Lee]

Hello all,

Ive a problem with the a/c on my 98 chevy lumina,ive tried to research this problem on my own , but.......

Ok, when your driveing the car ( constantly moveing 20mph+) the a/c works great, in stop and go or at the drive thru, in the parking lot of wallie world HEHE, its awful, vent temps range from 55 to 70 degrees, if it gets to 70 the compressor shuts off and BAM 85 degrees air.
but once you get moveing,9 and by moveing i mean like 1/4 of a mile(or less)
ice cold air, ive seen it get down to 36 or so degrees on the hwy.
hell theres times ill park in the shade and the a/c will stay cold, sometime not.

ive had it professionally serviced, they thought it might be the a/c comp cycle valve, so they changed it, no dice, same problem, (hey at least the refunded me for the part labor), , the fans runs,but theres a bit of a lag time till the blow full speed like 10 seconds, there's good airflow across the condensor, ( no leaves or trash) the car has 126k on the clock ( i purchased the car in 2006 w/ 75k)


Iam totally lost, help :?:

[jeffcoslacker]

I guess the $64,000 question would be, if you bring it up off idle to 2000 rpm or so while sitting still, does the A/C start working normally again, or no?

Does it do it if you put it in park and idle too, or just in gear?

[jeffcoslacker]

Also does yours have the auto temp control or just the simple rotary controls?

Nothing weird like dual zone or anything?

[1979Lee]

Originally Posted by jeffcoslacker

I guess the $64,000 question would be, if you bring it up off idle to 2000 rpm or so while sitting still, does the A/C start working normally again, or no?

Does it do it if you put it in park and idle too, or just in gear?

Ist question

Off idel to 2000 revs, i get a slight drop in vent temps, say 3-4 degrees, thats all, its a strange a/c problem i know.

2nd q

Its just the simple rotary knobs,(thank god) no dual zone 4 me.

i Drove the car today and it still doing the same thing.........
i think i need to go find another 98 lumina and see if the a/c is crap like this one, how i miss R12............................................... ...............

[jeffcoslacker]

I have a '97 with 140,000 miles and it blows ice all summer, all conditions...so it's not the design, there is something wrong.

You'll have to get some pressure readings...unfortunately I don't recall what's normal in a 134a system at different ambient temps. If the high or low pressure limit switch is going bad, it may be cutting the compressor just from the normal rise in pressure when airflow decreases.

The compressor could be worn out and not able to develop enough suction/pressure at low rpm. You can see this in the readings when the pressure readings "chatter" at low rpm and are out of spec, but come up and smooth out when you raise the rpm...

Ever watch the compressor clutch, see if it slips/stops, etc? sometimes they can be worn and/or packed with oil and crud from a leaky motor and won't hold when the motor is idling...you can see the clutch slowing and even stopping momentarily at idle...

[1979Lee]

Originally Posted by jeffcoslacker

I have a '97 with 140,000 miles and it blows ice all summer, all conditions...so it's not the design, there is something wrong.

You'll have to get some pressure readings...unfortunately I don't recall what's normal in a 134a system at different ambient temps. If the high or low pressure limit switch is going bad, it may be cutting the compressor just from the normal rise in pressure when airflow decreases.

The compressor could be worn out and not able to develop enough suction/pressure at low rpm. You can see this in the readings when the pressure readings "chatter" at low rpm and are out of spec, but come up and smooth out when you raise the rpm...

Ever watch the compressor clutch, see if it slips/stops, etc? sometimes they can be worn and/or packed with oil and crud from a leaky motor and won't hold when the motor is idling...you can see the clutch slowing and even stopping momentarily at idle...

Apoligies for not responding back till today,

The compressor is quiet, and it dosent seem to be slipping ( the clutch)

Its almost worth changeing the pressure switch, i might just do that, on another car i had i did that and the a/c worked better.
as for the pressure readings, i dont have any way to check that ( no gauges)


thanks again

[Corndog Man]

Here is a really good site for AC questions. I used it when converting the Astro over to R134.

http://www.autoacforum.com/

and

http://www.autoacforum.com/categories.cfm?catid=2


Corndog Man

[jd-autotech]

it seems to me i had a car doing a simular thing and the orfice tube was plugged so new one fixed it right up

[jeffcoslacker]

Originally Posted by jd-autotech

it seems to me i had a car doing a simular thing and the orfice tube was plugged so new one fixed it right up

Yeah that's possible too...need pressure readings to see it though.