WINDSHIELD FOGGING UP INSIDE WHEN ITS SUMMER TIME. I NOTICE THIS PROBLEM WHEN THE WEATHER IS HOT(SUMMER TIME). MY WINDSHIELD WILL BE COVERED WITH LIKE A SMALL FILM AND IT GLARES WHILE DRIVING ON A SUNNY DAY. I NORMALLY CLEAN IT WITH A WINDEX TO CLEAR UP THE WINDSHIELD THEN AFTER A FEW DAYS, IT STARTS TO BUILD UP AGAIN BUT IT DOES'NT DO THAT IN WINTER TIME.

Leaking heater core, maybe . Do you smell anti-freeze inside the vehicle ? All of the windows or mainly the front windshield ?

2 possibilities:
1 - HVAC External Drain Tube stopped up with dirt, bee nest, etc. Hard to get to w/out a car lift. Need to clear and drain HVAC box.
2 - Leaking heater core inside HVAC box. Moisture from defog will smell sweet and be hard to clean off glass. Requires Dash removal and AC service to replace Heater Core. Very time consuming and Expensive A-Freeze fumes are also lethal if inhaled.

Try Solution #1 First, Least Expensive, Non-Lethal Condition.

if the fog is on the inside of windshield and does not feel oily i would look for a water leak into the heater asm or the vehicle. if moisture on windshield is oily,then the heater core maybe the cause due to a leak.
good luck! check UNDER the carpets for water!!

I had this problem too. this is very annoying, and also a safety hazard. After a lot of investigation, and a few trips to the dealer, the cause was determined to be a non-functioning recirc door. recirc door was stuck on, and humid air from the cars interior (wet shoes, breathing, etc.) was being passed directly onto the windows by the defrost system. Dealer closed the door, and it went away immediately. Recirc servo motor part was ordered, and replaced. good as new. was covered under pre-owned warranty. Hope this helps anyone else.

The hot and cold difference gives you that, usually in the morning, you can clean the windshield inside and apply Rainx Anti-fog here's the link to what it looks like, you can get it at Autozone Pepboys etc.
http://www.amazon.com/gp/product/B0009H5W66

Yes, that's the way it works.

check your vents on dash are not blocked. put fan on high and see if air is blowing up the inside of screen.

This can be caused by a heater core that is leaking inside the car, one way to determine if that's the problem, is if you can smell antifreeze. It is a 'sweet' smell, and is quite noticeable. If u don't notice this, I have to say this is a common problem w/ Hondas. I've had a civic, 2 accords (currently have a 92), and 2 Preludes, they are great cars, but they all suffer from fogged up windows in cold weather. One reason is that they are quite air tight, and the older models don't have the greatest defroster system (weak). Try and keep a window cracked open slightly, see if that helps.

Sounds like your heater core is bad. Have someone check out the heating system and possibly replace heater core.. that should take care of the fog problem also by enabling you to use the defrost... Good Luck!