Mr. Wizard, need your advice! Cooling/A.C./Engine temp. related question!

[99VPRGTS]

Okay, heres the deal. My coolant level appears full (according to the guidelines in the service manual) and so does the overflow bottle (the bottle is just under max line).

Here's my problem. After the engine is warmed up, when I am sitting at idle (or in stop and go traffic), the engine temperature will slowly rise to just under 220 (the line 3/4 of the way over on the guage). As soon as the engine temp starts rising, my A/C starts getting less and less cold until it is about half as cold as normal.

Now, when I am driving on the highway, the A/C blows cold and the temp is pretty good on the engine...it goes to the line to the right of the 190 mark but doesn't get any higher.

I have blown out and inspected the condenser/radiator for obstructions and found none.

I do not know when the coolant was last changed.
I did try and service the A/C and it went okay but didn't help.

My next course of action is to have the coolant system completely flushed and then a 50/50 mix of water and coolant as well as a complete A/C vacuum and recharge.


Is there any thing else that I should do instead of what I listed above? Could it be something simple? I found a lot of info on this but no clear definitive answer for my specific problem and everyone told me to put a thread up here and let the Wizard offer his advice (or any other expert that has had experience with this problem).

My car is a 1999 GTS with 23K miles on it. Thanks!

-Brent

 

[Tom F&L GoR]

Actually nothing sounds really unusual except for the lower performance of the A/C. In my car having the A/C on at idle actually cools the engine because the electric fan is running at a higher speed.

That is something to look for - is the fan at low speed when it starts to get hot, then at high speed whenever the A/C is engaged?

If it's a '99 and you don't know when the coolant was last changed, you should do that anyway.

 

[QUICK SILVER]

Hey Chuck I met the guy that owns the Covette center in Newington CT. He asked me if I knew a good guy for the Viper so I gave him your number hopefully he calls.

 

[99VPRGTS]

Actually nothing sounds really unusual except for the lower performance of the A/C. In my car having the A/C on at idle actually cools the engine because the electric fan is running at a higher speed.

That is something to look for - is the fan at low speed when it starts to get hot, then at high speed whenever the A/C is engaged?

If it's a '99 and you don't know when the coolant was last changed, you should do that anyway.

Good point, forgot to mention that! Yes the fan is running at the higher speed when the A/C is on.

Hey Chuck I met the guy that owns the Covette center in Newington CT. He asked me if I knew a good guy for the Viper so I gave him your number hopefully he calls.

Hey quicksilver, do not come in here and hijack my thread. If you don't have anything useful to add to my problem, then don't post! If you have to get a hold of Chuck then take it to PM! Thank you.

-Brent

 

[jdeft1]

Sounds normal to me too...
Traffic means higher engine temp (probably not related to A/C issue) and less air across the condenser (even with the fan running)... which means higher refrigerant pressure and higher discharge air temp inside...

It's normal for the A/C to warm up a bit sitting in traffic or idle. It's normal for the engine temp to climb to 220+/- on a hot day in trafic.. It's normal for the A/C to cool down a bit at speed.

I'd suspect a low refrigerant charge if the disch. temp. swing is more than a few degrees....

my .02

 

[dave6666]

Here's my problem. After the engine is warmed up, when I am sitting at idle (or in stop and go traffic), the engine temperature will slowly rise to just under 220 (the line 3/4 of the way over on the guage). As soon as the engine temp starts rising, my A/C starts getting less and less cold until it is about half as cold as normal.

Sounds like the way that most of these cars operate. Hence, no problemo.

There are lots of things you can do to improve airflow and cooling capacity in a Gen 2. None of them do much more than squat stuck at a traffic light.

 

[hemihead]

Yup, totaly normal! The system is performing as designed.

 

[ViperTony]

It's normal. If you get your hands on a service manual, it details how the cooling system works and what to expect from the temperature gauge under various conditions/outside temperatures. Maybe get the AC refrigerant checked/charged but seems normal based on your descriptions.

 

[99VPRGTS]

Hmmm, well there has got to be a way to keep it cooler. What is the stock thermostat rated at? Can I put a colder one in there like a 160 or 170? Wouldn't that help keep it cooler?

 

[ViperGal]

What is your Tator's Stock number?

 

[jdeft1]

You can put in a cooler tstat but it'll still heat up quite a bit in traffic. Not sure but I think the stock tstat is 192(??). Hence, if it's running at 220 with a 192 tsat it'll probably run at 220 with a 180 tstat...

If it's a '99 you should do a good flush/fill and burp. Also,remember the temp gage in the car isn't the most accurate device. It's normal for the gage to cycle up to 225+/- then slowly drop back down to 190+/- ... Vipers run hot.

 

[99VPRGTS]

What is your Tator's Stock number?

Hmmm, I"m not sure. I tried your link and it said I didn't have sufficient access?

You can put in a cooler tstat but it'll still heat up quite a bit in traffic. Not sure but I think the stock tstat is 192(??). Hence, if it's running at 220 with a 192 tsat it'll probably run at 220 with a 180 tstat...

If it's a '99 you should do a good flush/fill and burp. Also,remember the temp gage in the car isn't the most accurate device. It's normal for the gage to cycle up to 225+/- then slowly drop back down to 190+/- ... Vipers run hot.

Yeah I'm thinking that a good flush and refill with 50/50 plus water wetter might help. So, you think that with a 160 or 170 stat it won't help? What about a better radiator? I do realize that Vipers tend to run hot but my biggest gripe about the whole thing is the A/C not being cold. I do have headers and am getting some heat shields...

 

[jdeft1]

A colder t-stat may help a bit for the engine...at least make it take a bit longer to heat up.... as will a better, aluminum radiator....(700-800 bux) You should search for info on water pump issues too... also a possible concern. I think there was an issue with '99 water pumps (I could be wrong)

The A/C is probably just a bit low on refrigerant....

 

[BigBadViper]

Doesn't have to be that way.

http://forums.viperclub.org/rt-10-gts-discussions/627096-cooling-problem-solved.html#post2711973

 

[dave6666]

...my biggest gripe about the whole thing is the A/C not being cold.

Depending on your climate, good luck getting the AC to keep you cold stuck in traffic. Mine works great on the highway, but setting at traffic light you're better off with the windows down.

 

[dave6666]

I think there was an issue with '99 water pumps (I could be wrong)

The water pump thing is 2001 cars - spinning impeller.

 

[99VPRGTS]

Ahhh ok, thats what year I thought it was too but wasn't sure.

 

[Viper Wizard]

Hi Brent,

914-763-3136

Thanks,
Chuck

 

[jdeft1]

The water pump thing is 2001 cars - spinning impeller.

Thanks, my memory only works good on really old cars....