Automotive Air Conditioning Information Forum

right off i have 2 generic questions 1. how often should the clutch on the compressor cycle off and for how long or does the clutch stay engaged. 2. there is a device called a thermal amp I think it's near the evaporator. does this sense the temp in the cabin and turn off the AC? could the compressor continually running with the AC on cause a temp spike in the coolant?
So here is the stats i found::

1. the temp gage for the coolant is slightly below 1/2 way w/o the AC on
2. both radiator hoses hot
3. looks like the clutch on the compressor stays on constant oh do you have access to all data. could u look up the low side high side pressure at 85°. what i found on line looks a little low
3. the fans are on when i turn the AC on and the clutch engages for the compressor.
4. so if i drive for about 20 min w/ the AC on the temp starts to spike whether surface streets or the freeway so at 70mph that would be mostly ram air and probably no fans...even though they are on.
so let me know what you think

need make/model/year

front and rear AC?

Anyone do anything to the system before your symptoms began?
What pressures did you come up with? Any pressures you find are merely a guide

"could the compressor continually running with the AC on cause a temp spike in the coolant?" NO in a well maintained system

Condenser fins may be dirty
Radiator fins may be dirty (bugs, moths, etc), or rad could be clogged internally.
Water pump impellor could be loosening on shaft.
What we do know, so far, is that the extra heat load from the condensor is triggering a higher temp than normal in the cooling system, and that it takes 20 minutes for that heat load to build up in the condensor.

1. Is your radiator original or has it been replaced?

2. Have your thermostat and cap been replaced?

3. Has ALL the air been bled out of the cooling system?

4. Sounds like this is NOT an AC issue

5. Didn't I respond to your post before?

thirdtbird Um it's in the title for my post, i left out Nissan , thought everyone would know that.

Crusser i bought it used, looking at the radiator it looks original, the car has 184k miles. , yes new cap and thermostat. someone told me to put the car in the over temp w/o going into the danger zone , and turn on the heat, if i get heat the water pump is good. i bought the car cheap, had a blown head gasket. i took the head off, was not warped, used a straight edge and feeler gage all in specs. chemically checked for cracks cleaned off the top of the block reassembled. whoever had it at one time used advanced auto's copper seal. supposed to take the thermostat out. i don't think they did, the thermostat was a bright copper color so i put in a new thermostat. yes i believe all the air is bled out used this https://www.ebay.com/itm/284112011135?h ... SwO6Bf09iK
yep i think its a cooling issue now too i am thinking whatever is wrong is what got the original owner. it's quite possible that you did did i ask the same question ? should i look for the post, think it's the rad. i bought the same year Nissan altima..has the 2.5L i took off the upper hose and the radiator inlet pipe crumbled. put in a new radiator ...uuugh plastic radiators, intake manifolds ( saw one explode , timing off or a stuck open intake valve) valve covers.. what are they thinking ?
what i think it might be is the actual neck of the radiator. i can sometimes smell that " pancakes and syrup" smell around the cap...the cap is new. oh BTW thanks for answering again

0utThere wrote: ↑Fri Jun 03, 2022 7:27 pm i bought the same year Nissan altima..has the 2.5L i took off the upper hose and the radiator inlet pipe crumbled. put in a new radiator ...uuugh plastic radiators

I think plastic/partially plastic radiators are common these days, and few radiator shops to fix them. I had the gasket between the top plastic part of my 1998 Frontier leak at its gasket (had to buy new one) and on our 2005 Yukon the plastic side simply exploded on the road. Good old cost saving and weight-saving projects !!!

Of course make/model/year is in the title, silly me. Not enough coffee.

Are you losing any coolant? Is it possible you still have a leaking head gasket?
Why did it leak? Did it overheat? If it overheated, the head is likely warped.
The best way to check a head for true is not a straightedge per se, but a virgin length of round stock, minimum 1" diameter, roll it all over the head, and use your feeler gauge.

Agree with Cusser that this is not an AC problem. Look at my suggestions

Also, use an infrared temp gun on your block, the gauge may not be accurate, we see this all the time. Has it ever actually blown water out?
Also, remove the rad cap, and run the engine until warmed up, and peer down the rad neck and check for bubbles (ie leaking head gasket)

In the mid to late 1980's--can't remember exactly--I worked on a Toyota Camry 4-cylinder with the same problem as yours. Removed the head, checked for straightness, replaced the head gasket, and reinstalled...same problem. Checked for bubbles (surprisingly, none). Turned out to be a very fine crack between the intake and exhaust valves in one cylinder that escaped my notice the first time. Had to replace the head (brand new from Toyota), which fixed the problem.

Of course make/model/year is in the title, silly me. Not enough coffee.

it happens to us all at one time or another

Are you losing any coolant? Is it possible you still have a leaking head gasket?
Why did it leak? Did it overheat? If it overheated, the head is likely warped.
The best way to check a head for true is not a straightedge per se, but a virgin length of round stock, minimum 1" diameter, roll it all over the head, and use your feeler gauge.

yep did that was within specs, used a machinists straight edge and feeler gage also used a 2 part chemical to check for cracks. no does not seem to use any coolant...oh if i go into the near danger zone , no boil over just coolant expanding into the overflow goes up a little over max, i think i get some evaporation of water. no bubbles in the reservoir. when it had a bad head gasket it would bubble in the overflow, and through the heater core i could hear a water sound like there was a bubble. i used one of those test kits to check for exhaust gas in the rad and it turned blue to yellow really quick. now stays blue...of course there could be a leak from the water jacket to the outside. oil looks good no mayo.

someone just stopped by will be back later

I assume this car's engine ignition timing is computer controlled.
If not, then check your timing, it may be retarded. A retarded ignition will make your engine run hot

Johnhere i used a 2 part dye and developer to check the head https://youtu.be/uaKniXEtE9k

Also, use an infrared temp gun on your block, the gauge may not be accurate, we see this all the time. Has it ever actually blown water out?
Also, remove the rad cap, and run the engine until warmed up, and peer down the rad neck and check for bubbles (ie leaking head gasket)

no boil over since i have had it. i used an infrared temp gun on the thermostat housing to see when it opened , never checked with the gage on the dash. use to bubble all the time in the overflow plus the heater core made a splish splash sound and no warm air at the stoplight before i did the head gasket. used one of those chemical test devices to check for exhaust gas in the rad after the new head gasket and 2 months later , test was negative both times.

I think plastic/partially plastic radiators are common these days, and few radiator shops to fix them. I had the gasket between the top plastic part of my 1998 Frontier leak at its gasket (had to buy new one) and on our 2005 Yukon the plastic side simply exploded on the road. Good old cost saving and weight-saving projects !!!

agreed on the repair of plastic rads. i can get a new one on Rock Auto for under $90. yeah i read something once about poly carbon fiber motors ....can't wait ...not. i remember my Dads 65' Impala, the whole radiator came apart. I am sure the 57' Chevy did too... i was too little to know.