Bustedf4i

Hello all,

91 sedan. 1.5 daily driver, pretty much bone stock.. getting a strange issue with the temperature..
The car has a.c. with that being said it works great considering the ef's age... anyway, prior to turning ac on I let the car warm up yada yada yada.. turn ac on, I can drive 20-30 freeway miles cruising 70-80 before the temp gauge starts to rise. It gets about halfway between half and the red zone. Sometime it will stay pretty close to the red zone and then proceed to drop down a bit then back up again. As I worry when watching this happen, I'll quickly turn ac off, turn the thermostat to completely hot and the gauge will drop down faster than you can say "**** it's hot outside!" So then after that, roll windows down and turn the t-stat to the cold position., cruise another 10 miles doing same speed, the gauge will gradually go up, then down and repeat. Is this a thermostat or a heater control valve problem? One of the two radiator fans?? I really want my ac back without issues. Figured I come here and ask if anyone else have ever experienced this issue before I go replacing **** that doesn't need it.. Any recommendations or info on this would be greatly appreciated!! Thanks.

EF.. = forever and always!! ✌🏼

94eg!

iTrader: (2)

Sounds like a cooling system problem. Bleeding the cooling system is almost always step 1. But if that works it will always leave you wondering how air got in there in the 1st place. Also I would replace the thermostat and the radiator cap if they were old. Also check your hoses for swelling with the engine running (best to check just before the radiator fan turns on). Also check the overlfow tank hoses and the plastic elbow in the overflow tank cap. If there is a crack in the elbow or hoses, it can draw air into the system every time the coolant shrinks (fan kicks on or you shut off the engine).

Sounds like your heater valve is working fine. If everything is working properly, you shouldn't need to open the heater valve to cool the engine. Vegas had temps at 114 last month and my CRX Si temp gauge never moved from normal with the AC on full blast for a 25 mile drive with quite a bit of elevation change.

Of course the compressor clutch eventually ended up shorting out....

Bustedf4i

Damn.... 🤔🤔 probably the best info I've heard yet! Much thanks bud!! I will definitely look into the info given. Sorry to hear about the issue with your ef. Things like that always happen at the worst times lmao! That will more than likely happen to me once I get this issue resolved. Been riding my moto.. it's beats sitting in a car with no ac in traffic when I can sew in and out of it on the bike. As of Monday mommy -in-law let me borrow her spare 05 pilot. That thing is a tank!! (At least it's a Honda!!) temps here in Ft. Worth averaging about 100 with heat index at 105-109. But it's a different hot here. I've been to vegas a few times. It gets hot there, but a good hot!!! Once again thanks bud!!

94eg!

iTrader: (2)

Oh....If you have spare cash, get this special funnel for bleeding your cooling system. I got one and I love it. Can bleed the coolant without spilling a drop sometimes. Worth every penny.

Bustedf4i

Ahh HELL YEAH!! I've seen those.... but wouldn't have thought about it!! Hell yeah!! Going to order tonight!! Coming thru again! Much thanks! 🍻

94eg!

iTrader: (2)

When bleeding, make sure to have the heater temp set full hot (no blower fan) and do the bleeding till the radiator fan kicks on at least 2 or 3 times. Otherwise you won't get the thermostat fully open (if it's working). It can take a while to get that hot simply idling. You should end up with steaming fluid in the funnel when you're done. Since you're worried about the operation of the thermostat, be sure to keep an eye on your coolant temp gauge the entire time. You don't want to overheat the motor.

BTW: There is a simple quick-check for radiator/condenser fan operation. Go do this check right now:
- switch the ignition to "ON" (don't actually start it)
- turn on the HVAC blower fan
- turn on the AC button
Both of your radiator fans should immediately start spinning. If not, you have a blown fuse, blown relay, blow fan motor or blown wiring. Go out and check this 1st.

Bustedf4i

Damn bud!! If your ever down here or I'm up there, the drinks are on me. I was actually going to check YouTube info during my lunch hour. Something you mentioned above had me realize something I forgot to ad in the original post. Anyway, what I forgot to mention was that, (this is what confuses me) when driving through town, say.. averaging 30-45 mph, or even at idle.. and idling all day if I please..... the temp gauge never moves.?. Apologize for the failed mention of that (ducking and weaving at work; no phones/ ya dig?) but it only does (mentioned in 1st post) at freeway speeds.... which does leave me to believe what you had mentioned previouslyabout air... a friend told me that it sound like a fan not blowing to its potential?.?. Said he had a dodge intrepid that was giving same symptoms. But I will definitely check into the info you posted. Very informative and I can thank you enough. Never have time to research these days... And thank the lord above we have "Honda-Tech" 🤘🏼

94eg!

iTrader: (2)

Amen!

BTW: If it sits and idles without overheat, then it's most likely not the fans. Fans are most important when idling. Especially in hot weather. This is also why your AC system works better on the freeway than on side streets. More airflow at greater speed keeps things cooler easier (unless something goes wrong).

schueytenten

Had a nearly similar problem with my 88 si recently. The gauge would act just like you stated in your post. As dumb as it may sound, I just replaced my POS aftermarket radiator with a new denso, and it seems to have fixed all the problems.

Bustedf4i

Glad lad you got yours fixed tenten... I haven't had the chance to look at mine yet!. I'm going to look into it possibly this weekend. If and after I blurp the cooling system and it doesn't do the trick, I may look into purchasing a new radiator, or flush it one..🤔.. going to start with the ez non expensive route first. Thanks for the input bud.. have a great weekend!! ✌🏼